Why is that ridiculous? Seems like a totally fine solution to me. Probably not possible in most cases due to licencing issues, but if not this is the best thing a developer could do. And making games and/or their servers open source isn’t even the only option. In most cases it will suffice to just provide server binaries and patch the game to make it work with self-hosted servers, or just patch it to make it playable offline. It’s that simple. Developing games with that in mind from the beginning makes this even easier.
Why is that ridiculous? Seems like a totally fine solution to me. Probably not possible in most cases due to licencing issues, but if not this is the best thing a developer could do. And making games and/or their servers open source isn’t even the only option. In most cases it will suffice to just provide server binaries and patch the game to make it work with self-hosted servers, or just patch it to make it playable offline. It’s that simple. Developing games with that in mind from the beginning makes this even easier.