It can easily be enforced because you know with a small playerbase like this it's not hard to spot a multi account if you pay attention, I've seen them before and so have other people.
Anyways that's not the point, it just puts things on a more even scale. Traders are still useful to fighters, and if you want to prep for your fighter that means you have to play a trader first for a bit instead of just doing both.
I know, multi account, can't enforce, blah blah blah but honestly if someone is doing that they aren't that great a player in the first place meaning I could care less about whether they cheat or not.