All of that is revisionist history at best. GitHub was a pile a shit long before Microsoft bought it has everyone forgotten when it would be a coin-flip on any given day if the site was even functional?
GitHub was in the right place at the right time to be a success despite the fact it's a massively clobbered together mess.
While I wouldn't necessarily phrase it this way, there is a chart going around social media that tries to imply that GitHub had basically 100% uptime right up until the MS acquisition. All it takes is either 1) having been there or 2) a cursory search of HN to know that this is a complete fabrication.