At least in the olden days, the DB migrations were not super solid, so you'd run into issues later due to that. But worse, it seems like every school has a few pet plugins that are absolute garbage but they have to have - and either aren't maintained, or have horribly broken upgrades.
And most schools started to get unhappy with moodle because it was hardly updated. IIRC they left the free moodle running at one major version and offered the service contract on the next major version up as a carrot.
I did look at putting up on my partners domain just so she's got an instance that doesn't rely on a client (she works for Universities). Last time I looked it was all "dump this .tar.gz php stuff into a directory", it was like going back ten years. No standard containers, debs, rpms, anything. Maybe I didn't look hard enough...
Drive + classroom is free as it the MS answer, I don't see moodle as a wise investment in time.
My partner works in higher education and they give her blank stares when she mentions how out of date they are. It's a culmination of "Not my problem" and "It works so why fix it?"