That's just foolish - you don't need passwords of any kind. In fact you don't need accounts. You can just store cookies, accessible from this browser only, which tells you what have you solved.
Re:Regex Crossword
by dr_zoidberg on Wednesday September 04, 2019 @08:12AM
(#20876348)
That doesn't solve login in from a different device. And if you cleanup cookies for whatever reason, you lost the progress. So no, cookies don't solve the same problem as a user account (with login from a "trusted" provider) solves for saving the state of progress by a user on this game.
Maybe allow both options for people who want to keep their saves across multiple devices and one for users that use the same browser. It is a pretty trivial thing to do.
They already do.
That's a game, an exercise for several nights
Which disappears cross device or cross browser, making users flood your inbox with support emails asking where their progress went.
Without speaking for Regex Crossword (I'm in no way affiliated with them):
I suspect the reason may at least in part be security. Passwords are dangerous to keep around, hard to handle, computationally expensive if done right, and if an attacker gets at the database, people get angry. A social network provider (especially the options here, Facebook, Google, Twitter, GitHub and Windows Live) is much more likely to get security (against third party attackers) a lot more right.