I don't think that it hasn't or couldn't, I think besides people in this thread saying of course it has, no one has shown one study confirming that. No matter how many times you spout your opinion, it doesn't make it fact. I've posted a scientific study, and a couple of articles that say the incredible increase in THC is a myth. Somebody post something to back up your position.
One other point...I, and several of the other posters in this thread have smoked both. I've grown and smoked some serious shit recently that was probably some of the best weed ever. But I've smoked stuff in the seventies that was it's equal. See, since I've smoked both, I can compare. If you haven't, you have no basis for comparison and your opinion comparing the two just isn't worth shit.
What has happened though is that I now have a wider variety of excellent weed to choose from. There is no argument about that.
I am glad we can agree that their is now an excellent variety of killer cannabis. However, I thought you might find this source interesting:
Pot is 10 to 20 times stronger.
In 1974, the average THC content of marijuana was less than 1 percent. But by 1999, potency averaged 7 percent.
Today’s sinsemilla … averages 14 percent and ranges as high as 30 percent.
The point is that the potency of available marijuana has not merely ‘doubled,’ but increased as much as 30 times.
- John P. Walters, Former White House Drug Czar
Marijuana is more potent than at any time since scientific analysis of the drug began in the 1970s, according to a report from the University of Mississippi’s Potency Monitoring Project. The average amount of THC in marijuana, the primary psychoactive ingredient in the drug, was tested at 9.6% --more than double the potency of marijuana in 1983.
The highest concentration of THC found in a single sample was 37.2%.
http://latimesblogs.latimes.com/booster_shots/2008/06/marijuana-more.html