If you get hit by Apple 0-day and infected with spyware, what good does changing the passwords on your accounts do? The new passwords would be immediately stole

If you get hit by Apple 0-day and infected with spyware, what good does changing the passwords on your accounts do? The new passwords would be immediately stolen anyway, unless you throw away the phone and get a new one - which seems pretty excessive reaction to opening a single web page, no matter how malicious.