It's not necessary to create a business account in order to start selling here. Regarding taxes though, if you ever collect money for selling something anywhere (online or not), you're responsible for reporting your income to your government. There's really no way out of that.
I'm not aware of any platforms that use an imaginary currency to simulate a store. I know there are people that want to use crypto currencies to avoid working with fiat money, but even things like that, if they become large enough, will probably be come regulated at some point.
I guess the point is, if you want to make money they you have to be prepared to take care of all the legal responsibilities. Once you get things set up it really isn't that bad though. In the united states it's a matter of filling out a few more fields when doing your yearly taxes.