While you're technically correct that they aren't running vanilla PHP, the main takeaway here is that if you want to ultimately want to scale to billions of users then you should probably use vanilla PHP, or maybe Python.
My point is that they started with vanilla PHP and then had the most successful scaling story of all time -- so if someone else wants to follow in their footsteps then they should go with what is tried and true.
Well that might be mistaking the chicken for the egg or vice versa. They made sure it works because they were heavily invested. So if anything, that is a story of a tenacious tech team and nothing much more beyond that.
Arguably picking almost any other tech would have worked as well because they would have doubled down on it as well and made sure that all the pieces that they need are in place and are working.
Thanks for elaborating, though I definitely don't share your conclusion.
