Thanks for all of the helpful replies. I think one reason this bothered me was that Acrobatics really wasn’t very good for...acrobatics. I mean, a lot of that involves jumping before you get to the balancing and tumbling. I’m also thinking of the super-agile, bounce-off-all-the-walls rogue or assassin type. (The Moon Shadow Elves in The Dragon Prince are an example.) They would seem to be more likely to have Acrobatics than Athletics, but technically all the jumping is Athletics.
Why can't they be good at both?