even if you steal my password (database)

That’s a big leap you’re doing there, equating stealing a password to stealing a password database. Those are very different. Stealing a password can be done through regular phishing, or a host of other methods that don’t require targeted effort. Stealing a password database, if properly set up, is a lot harder than that. It depends of course on what password manager you’re using, but it usually involves multiple factors itself. So equating that to just a password, no matter how strong and random, is just misleading.

Mind you, I agree that it’s less secure than “proper” MFA, and I’m not saying that everybody should just use MFA through a PW manager. I am using physical security keys myself. But for a lot of regular people that otherwise just couldn’t be bothered, it’s absolutely a viable alternative that makes them a whole lot safer for comparatively little effort. Telling them they just shouldn’t bother at all is just going to create more victims. There is no such thing as perfect security, and everyone has a different risk profile.