there is going to be plenty of times that someone is going to give up and close a trade that is technically in profit, but the commission alone puts them into negative at which point the broker has the right to pocket the commission because under their rules you closed a trade that was in profit. you gain nothing, and in fact lose funds.... for what normally would have been a profitable trade.
i think the key to all of this is that they aren't going to attract the type of customers who have an edge and who will actually be profitable. they will attract customers who can't trade anyway, so they have little risk, and will pocket the commission on the times the trader happens to close a profitable trade. that's their low risk high reward setup.
Congratulations ScalaFX for coming out of the closet!