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...