TBH I don't see any power creep - the best event girls were the early ones, which are now on general release, some of the best 5* were on release/early....if anything power has decreeped

As there is no real 'win' there can be no P2W, it's pay 2 waifu or support the game

...possibly as content comes out newer players may have the 'need to grind a little' moments where we've been keeping pace....so then pay to skip grind becomes a thing...