Exactly. Which is why it doesn't make sense for me to maintain all that signing code

You don't remove a security feature because most users won't use it. You make it optional, default to the simpler flow, and leave it there for the users who need it. Unlike a password, you can't reset an nsec. If it's compromised, everything tied to that identity is gone permanently.

What's the evidence for this claim? Why would 99% of people not click login with Amber if they understood the importance of it (click here to see why this is the safest option)? I'm struggling to buy that.

Agree. "Options"

Because most people can't get out of that old username password system. Even nsec and npub is way too much for most of themand they will leak their nsec one way or another. Even password managers should be a standard thing nowday but they're not. And another point is that 🍎 users can't have amber.