After stuff caused by the CoC modding scene (which I was too young to be around for), the devs decided that they don't like their games being modded and wouldn't allow mods for TiTS or CoC2 to be posted on their sites. I think that what happened was that some mods contained objectionable content (e.g. underage sex) and were circulated far enough away from Fenoxo's website that people didn't realise they were mods. (Save editors don't count as mods, probably because they don't actually change what's in-game.)
If I were to guess, the only reasons CoC mods are still up are because a) the mods with threads are relatively acceptable to the dev team, b) the CoC modding scene got large enough that it had to be left in for legacy purposes and/or c) CoC is complete, so event submissions are closed permanently, so mods are the only way to get new content into CoC.
Event submissions are still open for CoC2 (and TiTS), so if you want some particular content in-game, either you can get it in through official channels, or what you want is probably something the devs would never accept on these sites. And if you want significantly different game mechanics, you might as well make an original game. In all of these cases, there's no point in posting mods here.