Just want to put in a word for growers...not that I am one, so speculation only, but I was thinking that maybe they're growing these in long raised bed inside greenhouses because that's where they have space, so they're light deprived (Lynn as you suggested - put it in sun and see what happens!)
Also they don't necessarily use "fertilizer" as much as growth hormones, which they have access to, which is probably more efficient and cheaper for them then "fertilizers". If this is the case, then there isn't anything in the soil that will need to "wear off" it was probably sprayed on them.
Also if this is the case, than we probably will begin to see larger semps, that aren't because of "genetics" as much as artificial enhancers.
Just a thought. I'll ask Kevin about this when we have our clinic, to see if he knows, or has thoughts about these practices.