Well, stop and think about it for a minute: who would determine which words are acceptable and what would be the magical property of that person that meant that they were the "acceptable" person to determine such things?
If you actually probe your kindergarten teacher further about what intrinsically makes such-and-such a word intrinsically "unacceptable", I suspect they won't actually have a rational answer: it's probably their personal opinion, or possibly they've just "read it somewhere" etc ("Well, we were always taught that...").
Nonetheless, it's an interesting phenomenon that people seem to expect there to be some kind of authority or "right" answer. We've all been in the Scrabble game where your opponent has to look up a word that they use on a daily basis just to "check that it's a real word", as though the editor of the CA-CF section of their Collins dictionary had been bestowed with God's mobile number and was thus able to give "the" answer that no other human being was able to give.
The extreme of this is when dictionary definitions are used to settle legal disputes. One major computer hardware manufacturer, for example, quotes in its contract with developers the definition of "pornography" given by Webster's dictionary, implicitly bestowing upon that particular dictionary's editors some kind of legal authority to give "the" definition-- it would be interesting to know where the drafters of the contract believe that authority to actually stem from...