The problem isn't that you have to join a Discord or have an account to get something, the problem is is that Discord is a black hole for information that is completely un-googlable and doesn't allow for easy archiving.
If you want any answers to a basic question in a Discord, you're gonna have to either A. Wrangle with their abysmal search function, B. Pray that the answer is either pinned in the appropriate channel or in an FAQ, or C. Ask your common question and pray that someone doesn't yell at you for answering an already-asked question, get drowned out by people chatting in the same channel, or if the server is particularly dead, get a response at all. VS a forum or reddit where usually all the problems you can encounter have public questions and answers that you can just google.
Not only that, but when Discord inevitably shuts down, ALL servers and information spread throughout gets lost too. Sure there are programs to archive Discord servers, but who is gonna make all that public? Who is going to sift through thousands of messages of idle chat and meme spam in order to get to the discussions and information that actually matters? Whereas with web pages and forums, I have an extension on my browser that lets me send a page to the internet archives with a click of a button. I will archive this very post in fact!
Discord has its place as a casual IM and VC service, but it is an absolute dog shit replacement for forums and information hubs, and no one should be using it as such.