alt Hacker NewsGithub became successful long before those 'social media features' were added, simply because it provided free hosting for open source projects (and free hosting services were still a rare thing back in the noughties).
The previous popular free code hoster was Sourceforge, which eventually entered its what's now called "enshittifcation phase". Github was simply in the right place at the right time to replace Sourceforge and the rest is history.
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Technically so was BitBucket but it chose mercurial over git initially. If you are old enough you will remember articles comparing the two with mercurial getting slightly more favorable reviews.
And for those who don’t remember SourceForge, it had two major problems in DevEx: first you couldn’t just get your open source project published. It had to be approved. And once it did, you had an ugly URL. GitHub had pretty URLs.
I remember putting up my very first open source project back before GitHub and going through this huge checklist of what a good open source project must have. Then seeing that people just tossed code onto GitHub as is: no man pages, no or little documentation, build instructions that resulted in errors, no curated changelog, and realizing that things are changing.
And GitHub got free hosting and support from Engine Yard when they were starting out. I remember it being a big deal when we had to move them from shared hosting to something like 3 dedicated supermicro servers.
There's definitely a few phases of Github, feature and popularity wise.
In this vein, it doing new stuff with AI isn't out of keeping with its development path, but I do think they need to pick a lane and decide if they want to boost professional developer productivity or be a platform for vibe coding.And probably, if the latter, fork that off into a different platform with a new name. (Microsoft loves naming things! Call it 'Codespaces 365 Live!')