I think that is a misleading generalization in this instance. There are many instances in which dried herbs and spices are preferred if not necessary in certain recipes. If what you said were true then we'd be using bell peppers instead of paprika, but we do not, and to good effect. Dried spices have their uses and it's not all just a matter of convenience.
That said, given your claim, I'm going to try rubbing my next brisket with fresh crushed garlic instead of including garlic powder and we'll see how it goes. I expect it will be "different." Hopefully it will be better.
As far as granulated vs. powder goes, I'd like to hear why those that now use granulated over powder prefer it. I would have thought it was nothing but the the size of the grind and that that, given how it is used in rubs and BBQ, would not be an issue.
FYI, if you live close to a Trader Joe's, check out their "Crushed Garlic" in a jar. This is not that nasty chopped garlic in water. This stuff is as close to fresh tasting garlic as you're going to get. When I'm in a hurry I reach for it and it is like 85% close to fresh garlic.