As I commented here, there are some questions (at least that one) which would naturally fit with a
big-list tag. However, these tags are generally looked down on at Math.SE and MathOverflow. Is this a tag we should avoid on Mathematics Educators SE?
I think we should have a big-list tag or something related. It is somewhat unfortunate that OP presents this tag so negatively; it is true that on MO, for example, there are some issues around questions tagged like this, yet I would not know anybody having proposed to get rid of the tag. I claim would this tag not exists there would be more problems around these same questions; the existence of this tag is not the problem, in fact the tag is more part of the solution or resolution of some conflicts there.
The main reason to have it is that there are very roughly speaking two main types of questions (of course there is some grey area two). And, I claim this is more or less independent of the subject, and the same issue exist on various SE sites, not just the math sites (tex.SE has the tag, and Stack Overflow had the very same discussions as MO).
Questions that invite a somehow "complete answer." A common type of question on this site is such that it is reasonable to attempt a "complete answer"; of course this does not mean this answer would be the only possible one or the end all and be all for this question, but still there is a sense in which one attempts to answer the question as asked, completely, if one can; or as completely as one can. In this case, different answer while possibly complementary, can also have some considerable overlap and perhaps present one and the same thing slightly differently.
Questions to be answered by many partial answers. There is another type of question were the intent is not really to invite one or a few users to attempt a complete answer, but rather to invite a great many of small contributions that in their entirety create one answer. A typical examples is What are some great books for inspiring children to explore mathematics? another Good, simple examples of induction? Here, the intent is (I think) not to ask for (attempts of) complete answers, but rather for small contributions, everybody shares one or two of their favorites, and in the end one will have one "big list." (As opposed to each answerer collecting in their answer all the books they consider to be fitting as an answer, possibly partly duplicating existing answers. Same for the examples question.)
These two types of questions are so fundamentally different that they should be distinguished, in my opinion. It can even be useful to have special recommendations for such list like questions. Namely, it can make sense, for one user to give several answers, one for each item they want to contribute, or one for each type of item they want to contribute. To stay with the book question: in the long run such a question can be more maintainable and useful, if each book has its own answer, or if there are really many answers, books are grouped together along type and content (latter additions being edits to other peoples answer as opposed to new answers). By contrast, what happens with no special guidelines for such questions is that there is little structure as some books are together in one answer just because the same user happened to be the first to think of adding them. In this way the questions become more a collection of personal/subjective "I liked those best," which is not so much the intent of an SE site. But, with some special instructions in place, and some maintainance, such questions can become one structured resource of (expert) recommendations on a given subject. Having a tag to signal this helps this process.
It is true it is a "meta tag" and we could have several different tags that would not be meta tags for the same purpose, but this would make things somewhat more complicated to maintain and understand. In general, I am really against meta tags, but there are some that showed their usefulness on other sites that, yes, are different but then MO and tex.SE are not that similar either and both have it. One of them is big-list, another one is reference-request, which is also a pure meta tag, yet also useful, and we already have this one.
I think there are some questions appropriate to a
big-list tag (the one you mentioned; but also questions like "What are common mistakes in the field of ?", "What is a good reference for ?", but also the following questions here on the site: What are some great books for exploring mathematics? (not kids' books and not textbooks) or What are some great books for inspiring children to explore mathematics?
The question is: Will SE allow such questions?
Questions asking for a "big list" of examples, illustrations, etc. Please do not ask too many of these. Please do not use this as the only tag for a question.
This meets the first criteria for being a meta-tag:
If the tag can’t work as the only tag on a question, it’s probably a meta-tag. Every tag you use should be able to work, more or less, as the only tag on a question. Meta-tags, like [beginner], [subjective], and [best-practices], are useless by themselves — they tell you nothing at all about the content of the question.
Please take a moment to read the blog post I linked to, but the short version is that meta-tags break the tagging system and encourage behavior harmful to the community. This is a brand new site; no need to fall into bad habits right from the start.
Here's the MO tag wiki:
Questions designed to generate a "big list" of certain results, examples, conjectures, etc. via many individual answers, each contributing one or a few instances. Such a question should typically be in Community Wiki mode (CW); after asking, please, flag for moderators attention requesting the question to be made CW.
Again, this indicates to me a meta-tag. But it also reflects an outdated attitude toward Community Wiki. Here's our current thinking on that feature:
If we haven't said this enough already, questions rarely, if ever, need community wiki. What about answers? We removed the ability for users to make a question community wiki, but left the ability for users to make an answer wiki.
The intent of community wiki in answers is to help share the burden of solving a question. An incomplete "seed" answer is a stepping stone to a complete solution with help from others; an incomplete question is a hindrance and an obstacle to getting a solution as no one understands the inquiry. It is in answers that the goal of community wiki, for the community, by the community, shows its truest colors.
Yet even in answers, true collaboration is scarce. Most of the time, a single individual can provide a complete answer. There are even times where a question looks like it'll need a massive effort, but one gallant user steps up to the plate with an impressive and comprehensive answer.
Please don't create a big-list tag in the mold of Math and MathOverflow. To the extent the tag works for those sites, it's because of a deeply entrenched culture that need not carry over to this site.