I'm sceptical about this golden age when everyone could spell, punctuate and use grammar correctly.
I wonder whether working class people who couldn't do it took jobs where they didn't need it and middle class men took secretaries.
Now that manufacturing and heavy industry is virtually destroyed, many people are either unemployed or doing jobs where we notice their mistakes and tut over them.
I'm not saying that's okay but that we need to raise our standards of teaching now more than ever so that we can compete economically as a nation.
We could also have a go at making people feel worthwhile rather than sneering at them, possibly while making howlers ourselves. Self-worth is good. I know. I have a lot of it.
I had regular spelling tests but I don't remember formal grammar and punctuation lessons at my primary in the '70s. Maybe we had some instruction but luckily I was one of those people who was able to absorb the sense of it from books. I can't say what happened for anyone who couldn't do that but I can't imagine it's turned out well.
Dictionaries and grammar guides only work if you have an idea you're doing it wrongly. If you have no idea, you'll never notice.
People, including me, would benefit from better instruction than I had. But we need teachers, not just with knowledge but with flair.
It's true there are people who are good teachers but whose English language skills are shaky. I have few answers for that.
But we've all met people capable only of dinning instructions into heads without explanation and who ridicule or ignore children who don't get it the first time. They couldn't teach either but I never saw them get pulled on it.
But that's my idea about the skill of teaching all over. I admire it.
That was very long, but in my defence, you did ask about my pet subject. 
btw I would never start such a thread with fear that my writing was not up to standard.
Lueji beat me to it
.
My spelling, grammar and punctuation is good but I was cured of boasting about it when I wrote something snotty about other peoples' mistakes and my boss corrected it and pinned it on the wall. I don't want to revisit that humiliation except to say there was a lot of red ink on that page.