Damus had to make some sacrifices in order to do so. You cannot zap notes in Damus. Not without going to a separate website the app doesn't tell you about. You can only zap profiles without this.
Apple is antithetical to the Nostr ethos. Not much can be done about that, though, except leave iOS users high and dry, build a web app that can be used on any OS, or play by Apple's fickle rules.
Clients make different choices. Use the ones that you agree with and avoid the ones you don't.
Primal is optimizing for new users who may not have any sats to start zapping, so they wanted to have the ability to easily purchase sats from within the app. Anything that touches fiat rails will always require KYC.
It's not my cup of tea, either, so I will not be using their built-in wallet any time soon. In fact, I won't be using their mobile app at all until they integrate Amber login.
Yet, I can understand why they made the decisions they did, even if I don't agree with them, and I don't begrudge them for it.