Is it a realistic goal, particularly for a season with 50+ games? No! But it should be the goal a catcher strives to achieve each and every game.
Add in total blocks and successful block percentage, which is simple to record and calculate (but isn't done), and then you have a much better idea of who's a catcher and who's behind the plate because of their bat. MLB has figured out over the years that a good defensive catcher only needs to hit somewhere around .230 to justify being in the lineup. It seems that FP hasn't evolved to that stage yet.
Side note: IME, with a team that splits catching time, it often seems that the better defensive catcher gets paired with the wilder pitcher and that the #2 catcher appears to have equivalent or even better stats than the #1 catcher if you don't consider blocks/block %.
Should it be a goal? Yes! Is it the gold standard? No!
I totally agree with you concerning FP and lack of evolution concerning the advantage of utilizing a good defensive catcher.