Yeah I'll come out and say it, we don't need a bunch of Mary Sue's who can speak every language the world has ever known because they put a few points in a skill on level up.
An argument based on a somewhat sexist aspersion is not much of an argument at all. Your use of "Mary Sues" is not precise to its meaning:
https://en.wikipedia.org/wiki/Mary_SueThe reason I find your language sexist is the behavior in question has no gender association per se, but you are using a term with a feminine gender connotation to critique it. "Special snow flakes" is more likely what you mean.
In any case, it would be better to argue game balance, immersion, etc. rather than what "we need." As in the other thread about shield feats where you say "this isn't what the Prisoners project is about," that's a personal preference you are using rhetoric to universalize, rather than considering that others may have differing views from yours.
We RP that Perform can apply to every musical instrument ever known, as well as drawing, dancing, acting, and whatever else we want. We assume that with a certain set of feats a fighter becomes skilled with every conceivable weapon. Through crafting it is possible for a character to master diverse skills in a host of disciplines in just a few months. Do you have an objective reason that language needs to be treated differently?
What bothers me about posts like the above is the fear of true diversity underneath them. That is, they imply that only one view of RP is correct. Again, if polyglots break atmosphere, upset game balance, are difficult to implement, etc., those are legitimate criticisms. Characterizing someone else's preferred RP as acting like a "Mary Sue" I don't find persuasive.