I'm not sure that the world has become sensitive. Rather, opinions that people didn't feel safe to express about nonsense they experienced in their earlier life are now coming out. I recall a story about a church that held an "Aunt Jemima" event in 1991 and were surprised that so many black families chose not to show up - but none of those folks protested or said what bothered them. (https://theundefeated.com/features/it-was-past-time-for-aunt...)
Broad, sweeping statements about groups of people have been used to discriminate all over the place. They've been used to justify not teaching certain kinds of people, or to justify myths that certain groups of people "should" always be a certain way because of the majority trendline.
The people that built these myths sometimes did so (or do so today) with pseudoscience. So, for some who have heard this kind of nonsense their whole lives (maybe it was used to discriminate against a parent), actually valid + careful scientific research can sound like the same old nonsense.
The identification of differences between groups seem to be commonly conflated with the act of unfairly discriminating against a group with prejudice based on differences (perceived or real), which is kind of absurd when you think of some of the more superficial and obvious yet real differences. You clarify this very succinctly, but it is still abstract, and I find many people tend not to understand until given a more concrete example... this I find challenging to do without being prejudged as some kind of racist or sexist, so unfortunately I just don't bother any more, the world has become overly sensitive to certain subjects.