I've heard both sides of this argument for a while now.
From the DEA website- Marijuana is much stronger now than it was decades ago. According to data from the Potency Monitoring Project at the University of Mississippi, the tetrahydrocannabinol (THC) content of commercial-grade marijuana rose from an average of 3.71 percent in 1985 to an average of 5.57 percent in 1998. The average THC content of U.S. produced sinsemilla increased from 3.2 percent in 1977 to 12.8 percent in 1997.7
I mean that's 4 times stronger and they aren't even encompassing from 1970 to now. That's just 77 to 97. I would expect "newer weed" to be better as the sophisticated grow houses and even more discerning clients make it that way naturally. I guess they are only testing US produced shit but, when didn't people grow?
Obviously the pure sativa is a thing of the past and obviously there are other cannabinoids at play strain to strain. No one can argue with that. The fact still remains that the bud tests stronger. I don't know man in my experience the people that say todays bud sucks tend to be nostalgic for an old setting or have yet to stop smoking and have tolerances to match.
Personally I have only been smoking for 13 years. In my lifetime I tend to think that the bud has gotten better. Doesn't matter though cause no matter what there's always an older head talking about acapulco gold and thai stick lol.