

Discord, Reddit and Lemmy are bad choices for forums. If you want ANY useful information to stick, put it on forums you know are gonna get indexed and archived reliably. Reddit is indexable but there’s no guarantee the page will still be there when you search for it through Google.
Discord is completely unindexable so any information that exists on a server that gets deleted is lost forever.
Lemmy is a half-way house. As far as I know it’s kinda indexable but not really.
The one thing I don’t like about oldschool forums is that I have to make an account for each one. With each account comes a new place where your email address is registered, and a new password, with each password comes a new avenue for attack if you’re shitty about web security and use the same password (or a variation thereof) for everything. If you use a password manager you’re fine, but I don’t want my email being put everywhere.
There needs to be some kind of SSO that’s open source (like Google but not Google), so I can log into any forum that implements it, but with that comes the cost of running an identity provider and I don’t think forums are going to want to pay for that in addition to their own costs. Maybe some sort of distributed system or something where each forum donates a little bit of compute power to running the IDP, I dunno…