.., it makes more sense to upgrade properly.
Certainly !
nobody can disagree on that, however it might be more complicated..
A new P2 have much better tonearm & platter than P1, maybe there are other details too.
Notice antiskating on some P2 is fixed, NOT adjustable.
As for getting an old 90'ies Planar, then you really should aim higher than P2/P3 level, I'm not sure how much better an old Planar 2 is vs new P1.