Maybe. There are
surely gains to be made to sticking with PL-specific training though.
Instead of doing random XF-type ish and hoping it transfers over into something like better intramuscular coordination for powerlifting, you could do something with ~100% carryover and save yourself the extra time and effort.
As for the uber athletic PLers out there, that is somewhat irrelevant. There are a bunch of uber athletic football players that were better athletes than football players and they never made an impact in the league because of it. Everyone ITT knows of at least one uber athlete that failed to make it their given sport.
Just because said folks are athletic (the PLers) doesn't mean that athleticism is derived from their training; some folks are naturally more athletic than others. I'd look at the training regimen of top 'natty' PLers and see what percentage of their training is dedicated to specifically improving athleticism.
And not to be a **** (because this is all for the purposes of discussion), but also anecdotally, I don't train for any type of athleticism and from what I understand you do. You can backflip and hoop and do all sorts of stuff I can't and I prolly can't even touch rim from a standstill. And yet if we both step on the platform today we both know what time it is, even though you outweigh me and might have been lifting longer than I have.
Strength is a skill and powerlifting is a sport, so it's training still requires a certain amount of specificity.