That began in 1968 when they dumped the Hays Code for a joke of a ratings system(GMRX)
They proceeded to reshoot scenes to add most vile cursing, blood, guts, sex, horror, sex and more perverted sex.
I believe the new rating is “G PG PG-13 R NR (No Rating)”.
I went to Target a few years back and found a great package of 1950s Randolph Scott westerns. They refused to sell them to me as they were “Unrated” same as hard core porn. I had to prove I was over 18 years of age. I was 68 years old and looked every part of it.
I should mention I have watched NONE of these series on pay TV. Not worth my time.