gjohnson5, I think many would disagree with your statement that dumbells are for isolation. I use dumbells for seated presses and consider them to be an excellent mass building compound exercise. Also for bench, and stiff's. A dumbell can be just as much a strength and mass building tool as can a barbell.
I use dumbells for stiff-legged deads because they conform to the way I want to hold them, not me conforming to them.
The point of using dumbells with cleans and deadlifts is that it is simply ALOT harder to do. It takes more speed, greater arm and wrist strength, and greater forearm and grip strength to do them than with a barbell. Hypothetically speaking if my max clean is 225, then I would have to use a pair of 110's dumbells to get roughly the same weight. But the dumbells would be alot harder to clean than the 225lbs barbell and I know at this point I could not clean a pair of 110's, yet.
I like doing one arm deadlifts and cleans for grip strength and all around useful strength and power.
I like one arm cleans because it builds sorta awkward strength and it's great for grip strength.
I like using two arms to lift one heavy dumbell for cleans because it's a good awkward power building movement. It takes a fair amount of stregnth to clean a 150lbs dumbell to the shoulder with NO split or squat at all, just straight up to the shoulder in one quick movement through sheer back, hip and arm strength. My near future goal is to be able to 2 arm dumbell clean a 200lbs dumbell.
All these lifts are secondary to my main workout. The squat, deadlift and stiff, bench, press, row etc. all come first, but I like to add these weird movements in because they build stregnth and power. I may look stupid to some, but they won't be joking when I can clean a pair of 150's off the ground with no split or squat.
I think of my training as a combo of bodybuilder, powerlifter, weightlifter and strongman all in one, sorta, and I think all can be combined into a routine to build great all around strength and size.
If my gym had tires to flip, and stones and sandbags to pick up, I would. Least it has heavy chains and bands.
Well there's my long winded response to your post.