If you want to implement payment, that's clearly the wrong tool for the job :) (although, it could easily leverage cryptocurrency networks)

Personally, I see the dweb as internet of the early days, when we were all writing blogs and publishing tools just because we found it cool. If Dat makes it difficult for big players to launch commercial products on it, I would call that a feature (but it's too early to say if it's the case). They already have the web for that.