We expect contributors to sync and run all the tests. The public forking is the weird and unnecessary part.
Gerrit is the alternative used, and contributors have a full local clone of the git repo, with their commit, and that's private on their machine until they push it to Gerrit for review.
No-one said "disturbing". It's weird if you've come from an environment where you do your individual work in private, and only show it to people when it's ready to be committed/merged.
No-one said that that point alone is worth discarding the whole approach. You're nitpicking a single bullet point from around a half dozen points that stacked up.
Gerrit is the alternative used, and contributors have a full local clone of the git repo, with their commit, and that's private on their machine until they push it to Gerrit for review.