People can tell me if I am off base, but it seems to me that a growing number of new players' views about midranges may now be different than what was the norm 10 years ago.
Midranges, such as the Innova Roc, have for years been the workhorses in players bags, and you still see players like Philo Brathwaite throwing it to great success. But, putters have now become the workhorses in many player's bags. It now seems to be more common for players to throw putters in situations where one would once have chosen a midrange. We can now watch players like James Conrad, who chooses to throw a JK Pro Aviar X on just about anything inside of 350 feet.
If a person follows this model of choosing to throw putters, it may cause a change in how they view their midranges. They may not look to speed 4 and 5 discs, thinking that they don't find enough difference between those and their throwing putters to convince them to choose the 4/5 disc. But, if a disc were a bit faster, then they could see the justification for throwing it instead of the putter. So, maybe a speed 6 disc becomes the new "midrange" for them; the disc that they move up to from a putter.