The article is 80% about friction and confusion in trying that solution - from confusing prompts and endless questions designed to wrestle control over to local ecosystem, to use cases that just don't work with external vendor as opposed to native platform owner :-(

Which use cases don't work with external implementations, but do with the first-party one? I have yet to encounter one on iOS and macOS.

https://github.com/keepassxreboot/keepassxc/issues/10374 Passkeys not working on certain sites

I suspect 1password also has at least a few sites that need special handling

But 1password forces you to install the browser extension to do this.