I think Corbat420 is right in principal, not in delivery (ie. insulting people isn't going to get you anywhere).
Root binding is very real and a fact for just about every plant on earth. A plants foliage growth and braching is directly correlated with root growth, once root growth is retarded for any reason, top growth will be retarded as well. This doesn't mean that the plant will die, it'll just slow growth. This is fact whether it be soil or hydro. I'm using a drip system with hydroton in 1 gal pots, and once the plants get to around 2 feet high, their growth slows considerably. They're still healthy and are still able to flower fine, they just won't branch so much anymore. I'm 100% certain that if they were planted in 5 gal pots they would continue growing with gusto far beyond the 2 feet I get with 1 gal pots, however, most indoor growers (myself included) don't want a lot of vegetative growth, so I start flowering long before the roots bind, at around 1 foot tall, that way by the time they are finished they're about 2 feet tall and are making maximum use of my 2 x 600w HPSs.
So in conclusion, I think the statement here is that you don't need overly large pots when INDOOR growing because a) we typically only veg for a month or less b) the plant need not get bigger than necessary so it can make maximum use of the limitations of indoor lighting.
I think everybody can agree that it's counter-intuitive to attempt to grow a 6 foot tree in a 1 gal pot, and conversely, a 1 foot bush in a 10 gal pot. I think the general rule of thumb is to use the right container size for the target plant size. If you are growing 10-12 plants in SOG under a single 600w HPS, then 1 gal pots would be plenty, however, if you are growing one or two trees under the same 600w HPS, then you would use a 5-10 gallon container. This just makes common sense.