Since when did saying “f**k” become acceptable?

Warning: Old fart rant ahead
That “swearing is a sign of a deficient vocabulary” was a theory oft repeated by my teachers as I was growing up in the 50s and 60s. (A quick Google search shows this to be inaccurate.) But trying to limit my use of profanity is not because I am concerned others may think me stupid.* It is because of a single observation once told to me by a supervisor.
During my college “gap year,” I had two manual labor jobs. The first was as a hod carrier for a small masonry company. Hod carriers mix mortar, set scaffolding, and haul bricks and blocks around. I held the job for about six months and then was laid off.
My next job was delivering furniture and appliances for a large store. My supervisor and I would load up a van with sofas, tables, refrigerators, and such, and take them to customers’ homes. When not out driving about, we cleaned and rearranged the showroom.
One day, shortly after starting work at the furniture store, my supervisor pulled me aside and commented, “Doug, do you know that you never say a single sentence that doesn’t have a swear word in it? I don’t mind but our customers might be offended”
I was embarrassed, not realizing that after working with my very profane co-workers on the masonry site that I had picked up some of their linguistic habits. And on that day and after, I made a very conscious effort not to swear.
Since I wound up going into the field of education, this was a good choice. Classroom teachers, librarians, and even tech directors are expected to serve as good moral examples by watching their language. I believe I did a pretty good job of this.
I have always reserved the right to say “damn” or “bullshit.” But any swear word I use, I like to think I use intentionally. As I wrote back in 2019:
But it seems the world’s tolerance of even the most offensive profanities has changed. One cannot go to a store without seeing someone wearing a t-shirt with “f**k” on it. Jon Stewart’s Daily Show scripts now seem half comprised of some form of “f**k.” And nearly every Netflix movie warns views of the bad language that is to follow. I remember the day that three bad words in a movie would earn it an R rating and no one under 17 could watch it. Those were the days.
In comparison to other world problems, I suppose this is minor. But to me profanity is simply sand in the lubricant of a respectful society. Maybe I should just say, “F**k it” and worry about more important issues.
* There are plenty of other reasons for others to doubt my mental abilities.