it's a myth. if you compare top quality of the past (the colombian's, acapulco gold, se asian strains) to the top quality of today you'd find little to no difference...perhaps even find the best of old are better than what's around today! i have yet to find anything as strong as some nam weed smuggled in around 69-70...there's just more high quality around nowadays due to all the growers and a few breeders who know what they're doing.