Well, I don't think he actually tried it - he only said that people bough a lot of it. But may be just because of the price as they sell the SEM5 for like $20 and the SEM6 for $40. What made an impression to me when I was looking at the SEM6 box though is that it has an insanely long cable 3m and judging by online info the SEM5's one is the same length, which is quite curious.
This, this, this and this again.
Long cables = not portable use.
This isn't to say that all "desktop headphones" are awesome, but there's a lot more garbage in the portable headphone business than the desktop side of the house.