I don’t know that I agree with the premise. It’s not that people don’t want you correcting grammar because it removes a signal. I think it is more about people who use grammar as a means to attack and discredit a person, rather than the ideas presented. It can be used as an ad-hominem attack.
I think the other part of it, which is not trivial, is the rise of phones. People are typing on little keyboard and auto-correct can have a heavy hand. People don’t want to be judged for auto-correct getting one word wrong, invalidating a legitimate argument, so they look past potential auto-correct mistakes from others. The Internet has become much more tolerant of misspelling and mistakes, for better or worse.
If it’s a clear knowledge gap, then think a correction is helpful and warranted. For example someone saying “mute point” or “per say”. By all means, let them know. Ironically, auto-correct fixed both of those and I had to go out of my way to mess them up again.