here's my take...everything I read says "yes". When I started my 75 gallon, I set up a 10 gallon qt. I qt'd a yellowtail damsel for 2 weeks. At the same time, I added a clown goby to the main tank, can't remember why I did it. But anyway, they've both been in the 75 for about 3 months now and are fine. I bought 2 perc clowns and put them in the qt. They did great for 2 weeks, then got ick and died. bought 2 more and put them directly in the main tank, they've been fine for about 1.5 to 2 months now. bought 2 bangaii cardinals and didn't qt, they've been fine for two weeks now (knock on wood). I've only got 2 more fish to go before my tank is stocked, so I will probably not be quarantining.
the two most important points for me are....
I'm buying from a guy that I trust and have not had any problems with. the first two clowns that died came from a different lfs, and I will never buy another fish from them, even though the damsel came from them too.
secondly, imo, the 10 gallon was too small to be a qt tank. if I had a bigger tank for a qt, I would continue to qt. but if the qt is going to be so small that it adds additional stress, what's the point of qt?
acclimation and buying from a trusted seller are the two most important points to me. I know that adding a new fish directly to my main tank is risky for my current healthy fish. but my last two fish are probably going to be a coral beauty and yellow tang, and I see no possible good that could come from trying to qt them in a 10 gallon for 2 weeks. also, you need to make sure to pick your fish and add them in the correct order...peaceful first, territorial last. that will cut down on undue stress when adding fish.