Is the increased availability of superior strength down to the fact that it's easier to grow in artifical conditions within the actual country where it will be sold...say the US or England.......Does cross breeding different strains mean that more varieties are available than back in the 60/70s thus making it more available??

I want to get to the bottom if this thing because there are a lot of opinionated people out there in the media or in the street who you know are talking bollocks but have great conviction and confidence in the myths that they are creating.