Ultimately, people that get banned from a site usually complain about it because they want something the site offers that they can't build themselves. People can distribute the source code without Github's help; what they offer is nice, but not essential. The community is hard to clone, though; and the community is a great way to get pull requests, bug reports, manage permissions, setup CI sandboxes, etc. (It reminds me a lot of YouTubers complaining about YouTube. The reason they don't self-host videos is not because it's hard to put an mp4 file on a webserver and let people download it. The part they can't reproduce is YouTube's steady stream of viewers and advertiser relationships. That is why they whine when YouTube demonitizes a video, but they don't leave the platform -- YouTube has something that they can't make themselves. Github is similar, though in my opinion, a lot less important.)