The above is not a critique but certainly a list of things that lead to the possibility of a repeat of the infamous Windows popup for every single action you want to do out of the box. This leads to either decision fatigue or a pre-programmed "yes, just do it" response from the vast majority of users.
I personally think it should be an all-or-nothing type of allowance for this reason. Maybe the better way would be tracking access to passwords in Keychain. ie: Chrome+Safari+Firefox have all accessed your credentials for google.com but only Safari has seen your iCloud credentials and only Chrome has seen your HN credentials.
I'm looking forward to iOS doing the same for contacts; there's no reason why WhatsApp/Telegram/etc need access to my entire address book if I just want to call Steve.
Why not? It works fine for Little Snitch.
And here it would be even less prompts, as it would just be every website I visit && have an login account at.
This is pretty much exactly how macOS Safari prompts, and has for several years, at least in Touch ID scenarios. It shows a suggested username/identity with a Touch ID icon next to it, presented just like a normal autofill suggestion otherwise.
The per-site prompt and the inclusion of username/identity are really good signals, and feel like they reinforce the opposite of Windows UAC. They definitely gate access in a similarly repetitive way which encourages repetitive acceptance. But they demonstrate prior authorization that would have to be manual at least once at some point before the prompt, and you won’t be promoted the same way for sites you didn’t manually authorize first.
It’s a good enough signal that I generally use it as my first line of defense against phishing/domain spoofing. If I don’t get promoted for credentials for a service I expect to have an account with, I’m immediately suspicious. That doesn’t mean I automatically trust or distrust on that alone, but it’s a pretty decent sniff test.
I'd like to see finer granularity, perhaps multiple web password vaults and a mechanism to allow certain browsers to use certain vaults.
It might also be nice to specify which passwords could be accessed with which kind of authentication. Unfortunately the current system password dialog is easily spoofable - it really looks like a questionable javascript popup.