The problem is you can pay to unlock them or to accelerate your progress, which cheapens any achievement of doing it via grind anyway. Everyone will just assume you bought everything
More of a problem in multiplayer games where there’s a “keeping up with the joneses” effect pressuring kids to keep up with 40 year old dudes who just buy everything. That leaves a kid with 3 options: drop their entire allowance to keep up, grind with no life, or accept falling behind.
All 3 of these options suck
In early league of legends I feel there was the opposite culture, where you would get clowned on for using a skin especially if you performed badly