I would argue that if you can't communicate the purpose of the change in a simple commit message then you have probably combined too many things into the commit

I would argue that if you can't communicate the purpose of the change in a simple commit message then you have probably combined too many things into the commit. Breaking this rule is one of my bad habits and it's annoying for my colleagues to review and increases the risk of including some unintentional change ("I'll just edit this config file for some local testing...") as it gets lost in the noise.