So I think part of the attraction with GitHub is the integration of all 4:

1. Code review 2. Source browsing 3. Ticket tracking 4. CI

It does a mediocre job at all 4. But it does a good job of integrating them all together.

So I agree Gerrit is the superior code review model. but without the other 3 pieces you don't have a product. Even when I was at Google and working every day in Gerrit, I was dissatisfied with the poor integration between code search and code review and with CI.

Google3/Critique/Forge/etc -- Google's internal tooling -- did a much better job of tying that all together.