For socializing discord can match it, but it's really more the database of information that is searchable and viewable by anyone who doesn't even use reddit and it not being gatewalled that makes Discord not even come close. It's too much of a closed ecosystem even among discord account users with having to be in a particular server to benefit, and servers have been shut down and information all lost for members too.

Socializing to me is secondary. Like when it comes to stackoverflow, xda, or whatever random forums pop up in searches it's really the solution that's at the forefront of importance than whether these users are friends or whatever for anyone trying to find a relevant answer to their problem.