I dunno, game jams often produce great ideas that later can be (and historically have been) expanded to good full game.

Hackathons also create great ideas that later turn into fully-fledged projects. Game dev is just programming + art/design which is somehow something people feel entitled to for free even more than programming by itself.

To me there is a distinction.

Creating games is a more creative activity than programming (especially for programming in a hackathon).

Game jams is more similar to an essay competition than a hackathon, IMHO.

Because art/design is fun

I did a couple of game jams when I was a teen. They were incredibly humbling experiences that showed me the value of planning and communication, especially for a project with a tight deadline