Did film technology improve a lot in the 80's?

Seems this way to me, but I am no expert. Here is one thing that makes
me wonder. Back To The Future was made in 1985 and had all these
special effects. Could the producers have done the same thing in 1978
if they tried? And the size of movie theaters/cinemas seemed to double
in the 80's, and triple in the late 90's. I can think of a dozen
theaters in my area from the 80's (they have not changed much and seem
crappy now) that can play 8-10 movies at a time. But all the theaters
from the 70's and before are long gone now. And they usually had only
like 4 screens. The theater closest to me now opened around Christmas
1999 (right before 2000) and has 24!