I can’t speak for PvP, but vendor gear was never for “all” PvE gear.
Vendor gear was always catch up gear.
If you were buying gear, it was because you weren’t powerful enough to do the current tier of content, and you didn’t get enough from the previous tier.
As was noted elsewhere, we had vendors in Legion. And we have vendors now in BfA. The expensive pieces are there for that magic special filler piece to complete you set, not as a standard mechanism of general gearing.
I’ve posted here about the differences between the static and RNG system here: Top 10 complaints tomorrow - #95 by Piddy-uther