An adjustable allows for verying degrees of agressiveness with one razor. You could in essence get the same effect just by having multiple different razors of varying degrees of agressiveness if thats what you rather do.
The benefits of an adjustable is the convenience of not needing those multiple razors with multiple blades. At the same time, you dont really NEED all those adjustments either. 1 or 2 settings imo typically suits most people.
Adjustable razors are kind of aimed more for a one size fits all approach. 5 different people with the same exact razor and same blade all have dif requiremnets for what they want/need and at the simple turn of a dial that same razor can suit 4-5 of those 5 men while a single non adjustable may suit a some of the men of even none of them.
Basically with an adjustable, its easier to find that sweet spot. With non adjustables, you never really quite know if the razors right until you buy and try it. Tho the whole Goldielocks mentality of finding that 1 razor and that 1 blade combo thats JUST RIGHT can sometimes be the best... albeit... expensive part.. :-)
3.5/5.5 agressiveness vs adjustable MECHANICS?