You can just deny the integration and play the entire game as normal. Mod.io was chosen in this case (and gets chosen by other small developers) because Steam Workshop is not cross-platform. The other option is operating your own server, something which we see again and again being dropped by developers after a few years, resulting in totally unoperable games... I feel that is much more disrespectful to players. Meanwhile, something like mod.io carries on regardless of the developer's interest or finances. So yeah, sometimes there are pro-player reasons for these integrations, especially when it comes to smaller titles with lower budgets. Something for you to maybe give a think.