Thanks for the clarification. Unfortunately I’m no expert in the matter. I bet that some mods are compatible, I bet some aren’t. I bet some open source client/server pairing implementation might give more freedom but aren’t necessarily as popular. I have no idea how that impact culture or the size of projects. I imagine that the community of each project, e.g. Minetest, would know better if the limit itself is technical, e.g. mod compat, or not, e.g. network effect and thus a lot of people “sticking” to the “original” proprietary implementation not because it’s better but solely because their in-game friends are there.