It's not about identity as much as it's a very poor way to try to convince someone.
Don't base your line of argument on a statement you know the other person will likely disagree with.
For example "You should play Pathfinder because DnD sucks", holds no weight to people who don't think that DnD sucks. In fact if they happen to like DnD, it undermines your argument, because if you disagree about DnD, aren't you also likely to disagree about Pathfinder?
Well DnD consistently doesn't have criticals outside of attack rolls and death saves.
Like the person you replied to asked, what would you even expect to happen on an ability crit? If the DM only lets you roll on things that would be possible for you, then you would succeed on a 20 anyway. If the DM lets you roll on impossible things, then you have a 5% of doing the impossible. Neither option is good.
I absolutely let a 20 or 1 have extra effect whenever it makes sense and feels right. But having it be a core rule would be a PITA.
Not to mention that it would make skill checks even more driven by randomness, which is already a problem.