Over the years, a lot of things got added into all channels' Pinned messages. However, I'm guessing stuff in there don't get removed that often.
I just randomly checked #fab and #plugin-dev, and yeah, lots of dead links or expired information. I'm guessing this applies to a lot of channels.
So you might want to clean/prune some of those to make the lists more relevant, and also add some internal procedures to review those on a regular basis so as not to have some random annoying person from the server making a whole thread about that minor point every 5 years or so ๐