> The entire point is that developers don't want their apps patched

That's exactly what I'm trying to say. The entire point is not to secure the user, it's to secure the apps. It's working against the user's interest, as letting the user lie to apps is essential to user's agency. The technical means used to achieve this could also be used to work for the user and ensure their security without compromising their agency, but that's not what happens on mainstream platforms.

> No, you really couldn't.

Yes, you could. Exactly how you describe, so it was used only where it mattered, and in other cases they just had no choice. Today the friction is so low that even McDonald's app will refuse to work on a device it considers untrustworthy. The user does not benefit from that at all.