yes, I get the questions, I shoot with a sinar f2 and have the zoom back 6x12 it allows me to shoot my Fujinon SW 90 & 65mm f5.6 glass in a panoramic format, its easier to have 5 rolls of 120 in your kit bag than a dozen film holders, it is a bugger, yes, as its only 6 shots!, so one has to read the manual, go SLOW, so one does the right thing, but it gives a great alternative to larger formats, is cheaper, and also gives more surface area for wider lenses, as compared to 6x6 or 6x7 roll backs, aka it allows better aspect ratio so one can include more context to the subject.
One other point, 120 roll film is capable of being processed in any lab, and most do it, as easy as 135 film; sheet stock on the other hand is more specialised, so you end up having to dev. your own negs.