I see it as a learning tool, I guess. There is no mandating rule saying that is the only way to learn to play, but its a way to teach you to throw correctly. A lot of newer players jump right into the “biggest and longest” discs, but are skipping over the stages of releasing accurately, releasing into a headwind, form, technique, and all kinds of other stuff (that I, obviously, missed even as I still throw under-stable plastic).
That’s not to say that you can’t learn it, anyway, cuz I see a lot of people improving by leaps and bounds at Eastern Avenue (wide open course) without ever trying a Sidewinder/Valkyrie/Stingray, and jumping right into the Wraiths/TeeRexes/Firebirds. But, it’s a different story when he/she gets to a course that demands accuracy and “finesse”.
Eventually, it’ll probably all come together, but you’re not teaching yourself very much about how a disc flies by simply throwing something that will always hyzer in the end. If you teach yourself how to throw the stuff that is “harder” to control (understable), then controlling the easy stuff (stable) becomes easier.
Don’t take my word, though, I still struggle…