Initially, LinkedIn was just another site where you could find jobs. It was simple to use, simple to connect with others; it even had some friendly groups with meaningful discussions.
And then it gained monopoly as the "sole" professional network where you could actually land a job. If you are not on LinkedIn now, you are quite invisible in the job market. Recruiters are concentrated there, even if they have to pay extremely high prices for premium accounts. The site is horrible now: a social network in disguise, toxic and boring influencers, and a lot of noise and bloated interface to explore.
When Google decided to close their code.google.com, GitHub filled a void. It was a simple site powered by git (not by svn or CVS), and most of the major open-source projects migrated there. The interface was simple, and everything was perfect. And then something changed.
GitHub UI started to bloat, all kinds of "features" nobody asked for were implemented, and then the site became a SaaS. Now Microsoft hosts the bulk of open-source projects the world has to offer. GitHub has become a monopoly. If you don't keep your code there, chances are people won't notice your side projects. This bothers me.
Rant over. I hate internet monopolies.
I'm very split between Github (currently) providing a really nice interface/collection/way to access all kinds of open source projects and the obvious 'out-of-control centralisation' by the mega corp Microsoft.
It definitely got a little bit bloated the last years, but I still think it has a generally nice interface (browse code/review stuff, simple issue/PR system, simple way for CI via actions etc.).
But I really hope something like https://forgefed.org/ takes off someday, I feel like if the barriers are much lower to get onto a different network with the same user (without registering etc.) decentralisation can lead to more innovation in this space (management of all the stuff that Git doesn't manage itself, like issues, PRs etc.).
The beauty of Git though is that it's decentralized, so you can just mirror it on Github while mainly using a different platform. If you want a bigger userbase interacting/contributing with your project you'll allow PRs and issues there and if not just add a link to the README that points to the platform you're using...