why cant i set it to off and have to set it to hard instead, like why cant i completly turn cpus off. WHY?????

Because the rules specifically state that CPUs must be set to Hard. Setting them to Off or any other difficulty will result in your run being rejected.

i think he is asking "why the rules are that" lol

I haven't touched VS mode in a couple years, but it would give absolutely no challenge, it would be like a TT afaik. Correct me if I'm wrong, of course. [I probably am lol]

The rules are meant to be similar to the Grand Prix 150cc gamemode, but in VS mode. In Grand Prix 150cc, the CPUs are set to hard.