Why can't we make our own modpacks?

How come we can't make our own modpacks? I am new here, so there may have been something I've missed out on, but still, why can't we make our own? It seems as if it'd be simple, we just upload the mod to the console and perhaps even the config file for changes due to conflicting ID's I also ask this because I want TerraFirmaCraft in a server, and it'd be a lot easier if users can just upload specific mods to their own server to get proper specifics, not have to deal with unnecessary/unwanted mods, and if they just want one mod like me, it'd be so much simpler. Unless adding the feature/ performing the feature would be much more difficult than I realize.