Hydrogen's installation process was pretty much exactly the same as Element, the github README was just a lot less specific and there is no config file so you have to edit the HTML directly to get it to point to your site instead of matrix.org by default.
Part of why I was evaluating Keycloak is it can be self maintaining. I was looking to set up some related websites with common logins across them, and having Matrix (or another chat system - I'm still evaluating) was one of the services.
Anyway, Keycloak allows for self registration, users changing their profiles and setting their passwords etc, without needing admin involvement. I don't know if it does the password reminder thing (haven't got that far.)
But... if you're already using Active Directory in your organization, then the other option is just to hook Synapse directly into that. If you're using Office 365's version, then similarly you can either use LDAP to get credentials, or use Office 365's oAuth2 system. This all assumes you want a 1<>1 relationship between users on Matrix and people in your Active Directory directory. But essentially that's something you can set up and never have to worry about again, once it's set up it's set up and everyone has automatic access and knows their password without you doing anything.
One other possibility: it's at an early stage of development, but there's a pretty simple to set up/no admin needed (I can't even find out how you get admin credentials) Discord-like system out there called Revolt. It works, but some features like reactions are still pending. I mention it because you specifically mentioned Discord. I think it's at too early a stage of development to be comfortable with it, but it's progressing well so far.