I think its probably based on loads of really hard to pin down factors.A big factor IME is product/market fit.As an anecdote, my wife and I relocated a few years ago and that meant giving up her 10 year+ word of mouth referral clients. In that city we had no success with meta or google ads . In the new city with no client base she started advertising on meta with self produced ads and it was so successful she was at 3x revenue over the previous client base in 2 years.Still growing!

100% if this post (https://isolveproblems.substack.com/p/how-microsoft-vaporize...) is anything to go by, it could explain much of the scaling & reliability issues.Perhaps github not being built to scale this fast + being hosted on azure is closer to the truth.