This is (way) too long for a comment, so I am going to post it as an answer:
I am in basic agreement with the statements being made in the above linked question. Elementary and secondary teachers in the US are often incredibly lacking in mathematical content knowledge, and (perhaps more importantly) are often quite math-phobic, having been scarred by bad mathematics instruction when they were in school. Thus if this question is about whether or not the statements are true or not, I can't fault the answers that were provided to the linked question.
However, my understanding is that the real complaint here is one of tone. Whether or not we agree on the state of elementary educator's content knowledge, I do agree that the tone of many of those answers is unpleasant and uncalled for. There is a real problem in the preparation that elementary teacher have, but part of fixing that problem is engaging with those teachers (something that the original questioner seems to be attempting to do!). You can't engage with people if you harbour open disdain for them.
As an aside, this essay (with bad drawings!) is relevant, and something that I try to keep in mind. When I worked through my secondary education credential, I scoffed at the woeful content knowledge of my fellow high-school-teachers-to-be, and wept for the primary ed folk, who knew nothing.
Then I taught high school and middle school for two years, and ran back to academia to pursue graduate work in pure math—I simply couldn't hack it in that environment. I don't like the "babysitting" aspect of teaching (particularly at the middle school level—I don't want to act in loco parentis, damnit!), dealing with parents is scary, and I get frustrated with answering the same question over and over again far too easily. It still upsets me that elementary and secondary teachers are often very limited mathematically, but it isn't a personal failing on their part, nor is it even really their fault (no one every asked them to learn mathematics, and many of their elementary and secondary instructors were probably as ill-prepared as they are now—they had no role models). And they have skills and abilities that are quite valuable which I very much lack.