When these people say "commit" they're referring to the same concept you "merge".

I have branches that I work in and fork out from in every direction before merging everything back into master. My branches are messy because they're works in progress so I don't care about the commit messages. For the final merge back into master its a high-level overview of changes. I don't try detail every change. I honestly think that devs obsess too much over this clean commit history thing and that it looks to me like pedantic OCD.

I mean, git lends itself to a lot of approaches, the ultimate goal is that the master repo's main branch has a readable and logical set of commit messages usefully describing every change.

Personally I try to avoid merge commits these days, although that's more of a habit than any reasoned position, as such I make frequent use of rebase/squash to edit previous commit messages. Is that worrying about clean commits?

Not really, necessarily