What would be those? Serious question, not picking a fight.

There is not really a big disadvantage, is there? It keeps the .exe around in all possible versions without additional effort, even if external build dependencies were to fall away etc. Sure, nothing proper releases can't mostly achieve as well. But also not something bad.

It's a little bit like when projects include their dependencies instead of just listing them in a gemfile etc. Some hate that, but it can make things easier.

I've done this when we had existing scripts that were run after cloning a specific git repo, that then needed an .exe for reasons, and just adding the exe to the repo was the easiest solution so we didn't have to change all the existing tooling and processes.

Free bandwidth and boosting the engagement stats for their account among game developers, many of whom have github accounts.