I think there is a big advantage for bitcoin and other crytocurrency trading because the fees are a percentage of the trades. Also, the fees are very low, so you can make very small trades and the fees are almost insignificant.
Actually, the same goes for ECN brokers like LMAX or Dukascopy, where you pay commission and they are not part of the trade (i.e. they don't widen the spread, like Oanda, for example.) As for how low those crypto commissions are, Poloniex charges 0.25% for the taker (in their most expensive tier), while LMAX charges 0.0025% of the notional value of the trade. Granted, volatility is lower than crypto's (so you'll need larger positions), but not 100x lower...