It is this, plus more: - the web tooling must react properly to this (as GH does mostly) - comments done at the commit level are complicated to track - and g

It is this, plus more: - the web tooling must react properly to this (as GH does mostly) - comments done at the commit level are complicated to track - and given the reach of tools like GH, people shooting their own foot with this is (even experienced ones) most likely generate a decent level of support for these tools teams