I don't know how old you are. 1970's was my "high school" era, I lived thru when you are speaking. Writing,
I will agree with you as All but a few were of today "Audiophile" standards. ESL speakers as commented above I still highly regarded now. Speaker design and materials have advanced tremendously.
Now we have internet. Audiophile dedicated magazines. Reviews. Youtube. We had brick and mortar audio stores. Many as a side offering to their main business. TV repair and stereo shop. Best Buy! A small corner of Audio. What they had was what we were exposed to.
For a long time, The Voice of the Theatre speaker was the voice of the theatre. When you went to see a movie, that was what you were probably listening to.