I think one of the key points is how awful password managers are for non-technical people to use. It's not necessarily the developers' fault because it's difficult to interact with all the things they need to, but it makes it practically impossible to get someone to use one unless they're technical enough to be able to figure out all the random issues that come up all the time.
I'd love to be able to get some non-technical family/friends to use one, but there are just way too many times that showing someone how to use a password manager goes something like: "Okay, so now you've generated a password and you click 'Register' and... oh hold on, the page redirected for some reason and the pop-up to save the account info is gone, so, uh... well, I think there's a generated-password history page somewhere, let me just look through the Settings area even though it's not a setting... okay, there it is, so it should be this one. I'll just copy that and now I have to create a new vault entry for the site manually by typing in everything and pasting this password in there, and then..."
It's terrible, because a password manager that would just work and stay out of the way could make such a huge difference to general account security, but they all seem to still be difficult to use and require you to have a pretty good understanding of what's going on to be able to deal with random problems.