Thai stick was nothing more than somewhat-decent pot sprayed with a little hash oil, and while the sinsemilla of the time was good, they've had 40 years to selectively breed the best lines into the highest THC content.
The stuff that's around today is markedly stronger than in our time.
Contemporary thai stick yes, 70s thai stick no.
Remember, we’re babies compared to other cultures who have been growing it for years.