It is likely that most people do not pay much attention to whatever chemistry they learn in school, but at least I would have never trusted any plastic object to be in contact with food inside a microwave oven, even decades ago, when I was much less careful about contact between plastic and food at room temperature.
There has never been any reason to not trust microwaves themselves with food, because any undesirable effects caused by them cannot be worse than when heating food is done using traditional methods, at temperatures that are normally higher and much less controlled.
On the other hand, anyone who has some idea about the components of any usual plastic can see that it is practically certain that at temperatures not much above room temperature some of the garbage fillers included in any plastic besides the base polymer will degrade and leak.
There may be a few plastics that could really resist in a microwave oven without degradation, e.g. PEEK, but those are very expensive and they will never be used for a cheap article like a food container.
Already since a few decades ago, since I have first used a microwave oven, I have never used anything else but glass vessels covered with glass lids and I have always been astonished whenever I have seen or heard somewhere that there exist people who have the courage to put food in microwave oven in plastic containers, even if their vendor has the guts to say that this should be safe.
There is really no excuse for using plastic for heating food, as the only supposed advantage is being able to dump the plastic container without washing it, but the glass vessels used for heating food in a microwave oven are very easy to wash, much easier than washing vessels that have been used for traditional cooking or food heating.