It definitely had its downsides especially for the 1-dev projects. In reality it wasn't that bad. Code reviews usually pointed out where documentation was needed or would be helpful, and everyone was just senior enough where you could give them a feature ticket on one of these small projects and reasonably expect they'd be able to just figure it out if they had to.

Outdated or missing critical documentation, or too junior (or too lazy) coworkers would definitely have made this approach fall apart and that's a big risk of it IMO.