Ok, I've decided not to get into a huge argument over this.
But my point was primarily referring to maximum recruitment of stabilizer muscles, for which dumbbells are optimal. This is hardly just some opinionated nonsense I made up out of nowhere. Although I should have phrased my statements regarding barbells a little better, something along the lines of "and even barbells to a small extent." There can be absolutely no doubt that machines fail to recruit these muscle groups. I don't see how that can be up for debate, and I am not arguing that machines will not make you look ripped. I am postulating that people who develop their muscles primarily through use of machines will not look as good as those who develop their muscles through freeweights. And that if recruiting the greatest number of muscle groups will result in a better, more "natural" looking frame, then dumbbells would be more effective than barbells, although perhaps only slightly so (once again, I overstated that in my original post).
I was not referring to individuals who fail to work out major muscle groups like their rear deltoids, legs, and back. Obviously that looks retarded.
Sure it can be argued. There's no evidence for your claim, otherwise it would be common knowledge and practice across the weight lifting / body building community. And I've never seen any such thing like this.
Consider this - take 2 identical twins. Have them train the exact amount of sets/rep/weight for a year with the same diet, but have one use barbells and such sometimes and the other stick strictly to pully machines and dumbells. I bet you wouldn't be able to visually tell which is which.
Further, this idea that "more stabilizers are used with dumbbells" I'm a fan of sort of - you've got more control over the range of motion and you're going to involve portions of the muscle/hit it from angles you don't hit with a barbell. But how does that same logic carry over to a pully? Pully based machines isolate more. In order of isolation it is clearly going to be dumbell > barbell > isolation machines. And there's no difference between a pully or hinge based machine as far as the muscle is concerned - the range of motion will be identical. The force action might differ slightly but that's not going to involve any more or less stabilizers.
I emphasize the "sort of" though - stabilizer muscles are kind of a bogus term. If you're working chest you're working the pectoralis major. You can do a dumbell press or a barbbell press - either way you're hitting that same muscle. If you're counting on that lift to keep your pectoralis minor or your serratus anterior proportionate, then you're going about this wrong. Which goes back to my thing about the rear delt. Instead of doing dumbbells, just make sure you're hitting all the muscles, like I said before, and you'll be all good. But that flat bench or incline bench or other chest presses (close grip is good) are going to hit your chest in different ways than a dumbbell press or fly, and thus, are also important parts of the regimen too.
In summary, your theory is sort of all over the place and IMHO is shaped by pre-existing biases. In my opinion and 10 years of working out experience it's all about balance.
More types of exercises should always be superior to fewer.
As a final thought, it's possible you're confusing correlation with causation. Maybe you've noticed there are dudes in the gym that are bench monkeys or something - the typical low knowledge lifter who just goes in and does things like bench, barbell curl, etc. and maybe never got into reading about the science behind it, doesn't have good form, doesn't have good nutrition, etc. These types are going to have jacked up physiques but it's because of a bunch of other things than simply the fact they're exercising with a barbell.
