Both PS4 and Xbox One came out just as 4K was starting to get into market (prob a bit ahead of where 8K will be when PS5 launches), and it was frustrating that we had to wait 4ish years to get 4k support. Committing to 8K early means the same box will serve the early adopters as well as everybody else without a mid-cycle upgrade.

I generally think there will be limited urgency to upgrade to 8K any time soon (benefits over 4K seem incremental and we're not close to done w/ that transition yet) in the home, but love that Sony is making a strong stake for technical leadership.