Very few scanners will use sprocket transport for 35mm, really just minilabs doing scanning before it's sliced I'd think. Also much of the film community leans towards medium format/large format (if you're going to the hassle of dealing with film, make it worth it in quality, basically) which don't have sprocket holes at all.

Virtually all film scanners past and present use a film holder to make the film easier for the scanner (and the human) to manipulate and to offload the problem of film flatness to a sub-assembly. That's completely normal imo.

You are correct though that the film scanner market is dead as a doornail, film isn't exactly a high-volume business (however, afaik it is slowly growing however - that market hit bottom in the early '10s and Kodak/Ilford sales are growing these days). The entire market consists of the Epson V600 at the low end, Epson V850 Pro at the high end, and then Hasselblad makes the Flextight line at the professional end ($12-15k). Then you've got various old/discontinued models with varying level of support. So VueScan is really doing a solid here keeping that hardware in service.

One of these days I need to upgrade my V500 (predecessor to the v600) to a V850 so I can do large format on a flatbed. Right now I am using a Polaroid SprintScan 45 Ultra (which is a SCSI scanner that is only supported on VueScan anymore). I would love a Flextight but it's not justifiable and the options for a modern CCD (which, in parlance, is basically the opposite of a flatbed) are nonexistent other than that.