I think the point of the person you replied to is that it doesn’t make sense to use PPP for pricing. The dev charges x. They live from the money made paying the app. Just because a user lives somewhere where PPP is lower doesn’t change the developers costs.
Well you might call it exorbitant but that’s up for debate really. In my eyes it’s not exorbitant.
Especially given what a niche Lemmy is. So the dev might not even Break even on the costs.