A teenage English speaker said:

Respeak?

Re: A teenage English speaker said:
" . . . all of the authors don't feel like being told he/she made mistakes."

Is not well expressed at all. I would suggest that either the author is not a native speaker of English; or, if a native speaker, suffers from the all too common malaise (across time and across the planet) of language which results from speaking well the contemporary slang, but neglecting to educate oneself in the proper manner of speaking a language. This is badly enough expressed that your guess is as good as mine in regards to meaning, although there is insufficient context to be certain.

If a native speaker, one of several meanings could apply. If in context, this refers to authors already specified, it might mean: " . . . all of the authors [already mentioned] having in common not wishing to be told that they [there is no plausible way to use, or necessity to use "he/she"] have made mistatkes." However, if in context it does not refer to already specified authors, then it might mean: ". . . authors [here a general statement of principle is being made, in which "all" is not only superfluous, but confusing to the expression] do not like being told that they are wrong." A better way of expressing the idea of this statment as a general principle, which does use "he/she" would be: ". . . an author does not like being told [that] he/she is wrong."

Whatever the context, it is badly expressed.

You've expounded so well, Set.