I recently read an online article that the thc concentrations were between 1 & 4 % in the 70's while today some strains are as high as 13%. 4% might not seem much but to be honest it is about my speed. I can't handle the higher concentrations. If only we had a time machine or a Delorean to go back. Lol.
There was high THC pot in the 70's above 4%. The shitty Mexican weed was not good and it was very cheap and common. People have grown this plant for a long time. It's nothing new to understand how to grow so it gets you high efficiently.