I think this is really unlikely; since https://news.ycombinator.com/item?id=34092956 I've been gathering lockout reports on HN and they're mostly things like adding a phone number to your account and then forgetting about that when switching numbers.
So I don't really think the OS is the right place for a password manager, at least not without some standardized interoperability.
Of course, that does mean that it's less universally convenient like the other commercial apps.
As usual with Apple stuff, I guess they're not interested in making it a better separate app because their value proposition is "use our frameworks and get this feature 'for free' "
Additionally, I share my LastPass with my partner. Probably not a setup for most, but we find it convenient.
All that is achievable only when the password manager is not tied to the system login.