I have well over 200 different passwords - some only used once or twice. But remembering them is not an issue - because I don't try to! As Which recommend I use a password manager (Keepass) so I only have to remember one password.
Problems with password managers include
A) That they are a single point of failure if compromised. For example, I do use Apple’s iCloud keychain, which is super easy and really really secure. But if my iCloud account were ever compromised, every single one of these accounts would effectively be hacked, in one foul swoop.
B) That the really really good machine-generated passwords it generates are impossible to remember. So if I want to log in to such an account but I don’t have my iPhone or other signed in iCloud device to hand, I’m stuffed.
So yes, password managers help to cope with masses of passwords. But a better solution is still to simply avoid using services that require password protected accounts. I use string passwords for banking, mail, etc. But for an occasional purchase from an online retailer, I just check out as guest - or if they won’t let me, I find a different retailer.