The point isn't that GitLab has more, the point is that running these things at global scale is pretty complicated, and everyone has problems. "Just switch to GitLab" is pithy but isn't in itself an actual solution.
You can self-host GitLab and have few, if any, incidents that get resolved very quickly. Worked for a company that had no incidents that I observed in ~3 years, now work at a company that had ~2 incidents in 1.5 years.
We have a self-hosted Premium instance and have 30min of downtime _every day_ while the database is frozen and backed up. We've been told that it's a known issue being discussed with GitLab but that could just be CYA. But in any case, it's the "at scale, while changing" that tends to cause problems.
Perhaps this is a continuing argument for self-hosting, especially if you don't have to expose the instance publicly. But then, if that's an option, you can also self-host GitHub (though I have heard less anecdotes about the stability of that).