Your speculation is that their competitors would naturally not see a commensurate increase in instability while “only” handling 20% of the same crisis?

I don’t buy the excuse. I want to hitch my wagon to those “mysteriously lucky” competitors. (And have. And haven’t had similar issues to Github, since.)

Competitors would be long tail, so a different mode of traffic entirely. Maybe they get spikes that are more easily whack-a-moled than the constant hammering that GitHub receives.

Tough to say as this is all speculative, though.

It's probably a threshold thing isn't it? You wouldn't get 20% of the effect at 20% of the traffic. There's a step function in there somewhere.