I've been regularly sending patch series to Gerrit, and it works fine. If you're not seeing the previous review comments that's because either (a) you're not adding the Change-ID: lines, or (b) you haven't tried diff'ing against the previous version of the patch (in which case the review comments will be clearly visible). Also, the review comments show up in e-mail, of course.

It's true that Android uses a lot of cherry-picking and rebasing, but that's because they have to support a large number of releases. That's a development process choice that the Android folks have made --- but it's not fundamental to Gerrit.

At least the modern versions of Gerrit have a lot of configuration options, some of which can be set on a per-user basis (via ACL settings). It's certainly not perfect, but it is actively being developed, and it is getting better...