IMO the LLVM community could learn a few things from the Rust team. I know that the activity level is not the same but it's really encouraging to new folks that reviews get engagement and disposition: "this is good, but fix that" instead of wilting without any clear indication of whether it could be merged.

Also, the fact that the CI triggers and lets you know whether your change causes any collateral damage before you merge takes away a lot of the fear factor of contributing. This is also in stark contrast to LLVM's "merge it if it LGTM, revert it soon after when we find out what it broke."