The slightly longer answer is that this is one of those "classic environment vs. classic knowledge" things: far less people on live knew that Soulfire could be used that way.
It's also one of those Blue vs. Live/Green things: because people here have had so many extra years to pimp their characters, they've got (comparatively) nothing better to do then pick up a Soulfire. On live (and presumably on Green) most players would be too busy working on their epic, or some other quest that was actually meant for their character, and then by the time they'd finished all of them there would be a new expansion with new quests to work on.
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