I could make the argument that mod support can help add to a game's longevity. Look at games like Doom, Half-Life, and Skyrim. Games with huge modding communities as well as fan support long after their original release. Heck, some games originally started as mods before becoming their own thing. Look at Team Fortress, The Stanley Parable, and Counter-Strike for example.
Ordinarily I would agree with you, but I think the message Shrike quoted provides some extremely valid complaints about it in this case. CoC2 isn't like Skyrim or Half-Life, it's a much much smaller text-based game that you download as a zip file off a fairly obscure blog site (I know it's on Steam but the playerbase on there is
tiny). It's much easier for the waters to get muddied than for a game that you almost exclusively get through big public channels (barring piracy), and especially so when it's an indie game developed by a small team vs a well known studio.
You don't find a .zip file with the entirety of Skyrim plus snuff sex mods on a suspicious forum and go "Wow, why would Bethesda include that?"
Also, this game updates monthly(ish), and mod communities get really annoyed at games that update frequently. I say this as someone who recently had to spend two hours fixing my mod list due to Steam autoupdating Fallout 4 lmao.