A major advantage is that they provide a large, highly visible image at an economical cost. For a stock agency, the difference between viewing a sheet of twenty 35mm images or a sheet of six 70mm images is substantial. The printer doesn't care. All it needs is a good file. Scanners are another matter.
Most scanners favor chromes.
I have a bunch of film I want to process, and all of the last labs I've used have scratched the film. All of our film processing is dip and dunk. You should be aware, however that it is possible to scratch film in other places than the film processor, most notably in the printer. We do take care to keep our printing equipment clean to minimize the potential for scratches. I have read very positive reviews of the LightJet 5000 laser printer, with many professional photographers claiming that this machine makes the best prints available today.