What is the alternative - fixed fittings specific to the part being attached to?
As others have said I have garmin and wahoo products and the bands are easily replaced or swapped. Useful when dealing with odd sized mount positions (eg aero seatposts).
Also on my bikes I often use two for things such as my garmin varia. I also add a layer of insulating tape which stops them rotating and lessens teh chances of teh band being rubbed, breaking and the whole thing disappearing as opposed to spotting it flapping held on finally by the tape. And it is more aero on my TT bike.
Just a thought.