I saw that as another form of projection, actally even a way nearer to looking at slides on a lightbox, than on a reflective screen.Apart from projecting, there are dedicated slide viewers that present a nice experience for casual viewing on the go.
I have projectors that incorporate a rear projection screen, but also yield the possibility to project on a big, reflective screen. I got the impression that such dual-use projectors were more a european thing.

