Most of them don’t, but some do. Just like with programs and apps.
Do they provide ethical installers?
They don’t provide any, you just download the game itself. Or you can use their Free Software client, which will download and update the games for you.
But to get there I have to use unethical proprietary software that I hate so much.
Who said I do?
Of course. This is why itch.io is better than gog.
Have to use that to get more unethical software. I see no problem.
Games don’t come with the source code. It’s unethical software by your definition.
Do they provide ethical installers?
Most of them don’t, but some do. Just like with programs and apps.
They don’t provide any, you just download the game itself. Or you can use their Free Software client, which will download and update the games for you.