As someone with high privacy focus, just having a user id given by stripe, that stripe then can connect to a real person is a liability. Mullvad allows payments in crypto and their site is accessible as an onion service. I know it definitely adds overhead to do both of those things, though personally I wouldn't mind paying a lot of extra for it. I'm not sure which fraction of users are like me though, I might just be an unviable customer

Sure, but also note that it took 14 years for Mullvad to reach the point where it can support all those billing methods. Kagi launched less than a year ago with a small bootstrapped team, building a much more complex product.

Kagi can listen to its users and learn from other pro-privacy companies. Imagine if proton requires a paid account for everything for everyone.