From a player standpoint, it's a benefit.
If Jayden Daniels declared last year, he would have been a day 3 pick. Probably would never see the field. Going back to school (likely due to NIL) has him positioned to be a first rounder.
I'm really surprised JJ Mccarthy declared. I thought he could use an other year. I don't see him as a first rounder, but that's just me. Feels a bit like Will Levis where it's more projection than production.
there's never any point for a QB to declare early unless they know they're likely to be a top pick