Well MH, from reading the firt part of the Christopher book I got from you, I've gotten the impression that herbs are just about anything and everything that is green and growing. Somewhere along the line, we've been conditioned to think of green and growing things that we otherwise don't know much about as "weeds", with the implication being that weeds are useless. Just one of the many weeds that Christopher regularly put to good use was Plantain; I can now walk around the neighborhood and quickly spot it, it grows just about every where, even in most back yards. It grows so well I guess one could say it grows like a weed ;)
Considering this, if "they" want to eradicate herbs from the planet, then it seems they must basically nuke the planet of all things green and growing. Not that they won't try, being as stupid and arrogant as they are, but nonetheless a tall order to try and pull off even for the likes of them. I suspect R&D in genetic methods (like GM'd veggies that are becoming more common) is part of this plan to corrupt "herbs".