Well, one is that you aren't on the hook for supply current,
because all the energy comes from the RF and LO inputs.
A Gilbert (or a passive with on-chip drivers) consumes
supply power.
The commutating mixers (FET quad) want a pretty stiff
gate drive and you may find them not integration-friendly
because the driver you'd need, will throw a lot of glitch
energy back into the rails.
My company makes passive mixers which are great as piece
parts. But when we have to integrate a lot of radio, at low
power, here comes the Gilbert.