If you need longer lenses rangefinders don't cut it, but they're great if you primarily use one or two standard to moderate wide angles, which many photographers favour. Their main advantage is they are more compact than SLRs, and they remove the viewing system from the lens, which is also potentially their biggest disadvantage.
Compact SLRs like the Olympus OM and Pentax ME/MX systems never really took off, partly because they didn't offer more than token compact lenses, partly because the fashion was to show how big your "gear" is, a tendency that still dominates DSLR photography today. Autofocus SLRs removed some of the disadvantages of the reflex viewing and focusing system, at a weight and size penalty. In 2016 small film cameras are prized, financially, big ones less so.