Yes, this is the main purpose for 3d models is to show the quality of your work and sometimes it's not enough to just show screenshots with wire-frames, nice render etc. Lot's of people want to "touch" the model. C'mon, even serious firms post free downloadable 3d models to let people see the quality. Like this guys: https://www.artec3d.com/3d-models They sell scanners, but they are not afraid to let people to download examples. Even if user can scale and rotate the model in the viewer. I've also read a research by one guy (can't find the link, sorry) on Turbosquid. He'd found that artist who had good free models had more sales of their payed models.
In other hand, you can't stop altruists from sharing their models for free.