Not arguing, trying to follow the logic. You could be asking for one thing but thinking of something else. I’m trying to be helpful, I don’t mean to be rude.
The problem with your example is that if you come across a login page your first instinct should be to open your password manager and have it fill in the password. You’ve moved on from keeping passwords in your head and now use a password manager. If you don’t have an account in your password manager for this website yet you’ll realize this once the vault is unlocked and then can take the steps needed from there.
If you’re entering passwords manually then why have a password manager? You should be opening the vault to have it fill the password to not only make your life easier but to protect you from phishing pages. If you don’t have that login yet you’ll realize this once the vault is unlocked and then add it.