Thanks!!
I say "soft" ban because there are exceptions. I don't mind huge patch sets if the changes are proportionately trivial: One example is mechanical search-and-replace jobs on large codebases. But the 3000-line new module that just gets dumped on reviewers all at once is in bad taste. It's the responsibility of the author of the code to ensure that it is broken up in a way that makes reviewers' job tolerable. My opinion.