The question often comes up: why a standard protocol? Among the many reasons is the illogicality of having to have multiple workstations just because a site may have building automation and control equipment from multiple manufacturers in the field. Would anyone tolerate a world where each TV network had its own signal format, each requiring the purchase of a special receiver? I don't think so!
(Thanks to Peter Macdonald, Cartoonist Extraordinaire, for this and several other illustrations that make the point far better than words!)