To quote the ISO standard 7498 in which the OSI reference model is defined: "This reference model provides a common basis for the coordination of standards dev

To quote the ISO standard 7498 in which the OSI reference model is defined: "This reference model provides a common basis for the coordination of standards development for the purpose of systems interconnection while allowing existing standards to be placed into perspective within the overall reference model." It always made sense to me that the OSI model should be used to guide the development of internet standards. I have always doubted the second half of that statement, about understanding existing standards from an OSI perspective and I believe that is the mental gymnastics of which you speak. Despite the mental gymnastics, out in the real world, me and my co-workers still find ourselves using OSI vocabulary to reason and talk about the networks we're working on. If I'm told that some random black box is a "layer 3 switch" I already have a basic understanding of what it does and how to use it, even if I'm not familiar with the vendor. That's value for money right there, in my opinion.