Shouldn't 100% runs require new account or no data due to the coin requirements for demons?

Would you like to create a new e-mail adress and a new GD account everytime you want to start 1 single run?

You could also just have one blank account, finish all the levels 100%, then go in account settings then load and thats it poof no levels no coins

Right, didn't think of that. It would prevent people from splicing.

doubt that it would prevent people from splicing, you can easily use a level percentage changer or level uncompleter

Even if they would, as long as we see they finished the level with all coins its ok

This would Not make any sense, any Run is easy to slice... sadly. Just get all the Coins while playing, the Mods will verify it.