What's the problem with discord?

I was looking at old posts and navigating my way through the sub because of boredom and saw that some of the old posts have a few people mad at the mentions of discord, and there were even a few that suggested the mentions of discord should be forbidden in here as Reddit is a separate platform. I understand that but that's where we pick up most of the guides though and even copy them here I guess, Incase I see someone absolutely clueless who I know I'm unable to assist in Reddit because of its single chat messages and each message being its own individual I sometimes direct them towards discord for extensive help. Is it really that bad? I've always gained help from discord for myself and I'm pretty new to using reddit I guess so there's some things that I might be missing about the platforms