Oh yeh, think Shimano have a new DA groupset
I remember when, upon buying my brand spanking new 8 speed DA setup with indexed gears (all very new and a 1st) - all my clubmates said...why do you need 8 sprockets...it's been the same each time a new sprocket has been added....apparently since freewheels went from 3 speed......
More sprockets mean a straight through block - 1 tooth increments...lets you pedal more efficiently as there are no big 'jumps'