It's not fair to blame users on this, because it's impossible to "teach" people to come up with and remember 100+ hard passwords and recall which service which

It's not fair to blame users on this, because it's impossible to "teach" people to come up with and remember 100+ hard passwords and recall which service which password belongs to. Passwords were the problem to begin with. Easy to implement, but extremely hard to remember and use correctly. MFA is part of the solution to this problem.