Right. I mean that is the thing, I guess. For people who just want to get some stuff done in a way that makes sense, TinkerCAD is about as low-friction as it gets.

It's also arguably better at hacking on STLs than a bunch of higher-end CAD packages; it feels like that's been a focus of their efforts.

Personally what I'd really like to see alongside it is a sort of Scratch-blocks-based OpenSCAD/Build123D type thing -- this may already exist?