Tony Vargas
Legend
I feel like the 'realism' argument is more to head off realism objections to what is essentially a playability concern.I think its unnecessary, but the OP was couched in terms of realism and making sense, so I'm engaging with it on the basis that this is the case, and in those terms.
Consistency would be another way to put it. It's not consistent that some things, like hps and weapon attacks, for instance, advance steadily for all characters, even though some are highly specialized in well for others it's an afterthought, while other things, also prevalent in adventuring, like exploration & interaction tasks and saving throws, don't, and net degrade as you level. You could also phrase that in terms of balance.
Skill checks /are/ ability checks, of course. But scaling ability checks would make a good deal of sense, instead, would make a good deal of sense.That's the point: Most of the "generic adventuring tasks" that others are saying adventurers would improve at given their daily regime, are ability checks, not skill checks.
Scaling ability checks, and /not/ proficiency - so proficiency provides the initial +2 mod, scaling happens at the stat - would be simple, elegant, address the problem of non-proficient characters falling further behind, and keep proficient characters (and those who invest ASIs in a given stat) noticeably better, at all levels.