I used to be regularly ridiculed for my poor mental arithmetic skills when I was younger - is this the same thing? Were people doing it to make themselves feel superior?
I suspect yes. Maybe not in all cases but yea generally!
I'm atrocious at maths! And when I'm anxious it's even worse! I've just made a total tit of myself on another thread (energy prices) cos I cocked up my calculations due to misplaced decimal point! (And damn near gave myself a heart attack in the process thinking I'd have an astronomical bill!)
The VERY kind pps on that thread haven't been at all condescending or patronising twats!
They've taken the time and the patience to help me figure it out - and calm down! And explained something to me in a way i understand that NOBODY else in my almost 50 years has been able to! Yay mn!
I’d guess it’s to protect a bank of words they hold dear, in other words, language they have learned and built upon
Which is daft anyway because English is one of the most mutable rapidly evolving languages in the world!
That said on very close analysis there isn't really even an "English" language because the VAST majority of our words are nicked from other languages!
We don't even stick to a group of related languages like the Romance languages or Germanic they're from all over the world!
But someone is bound to say language changes and evolves. Yes, yes it does. Even more reason to be precise then.
Damn it! Caught! 

However some mistakes should be identified and corrected. Elementary errors/misuse such as these are especially irksome because it could be confusing for the reader. “Your” vs “you’re” “Bear with me” vs “bare with me” “Then” vs “than”
But what gives you the right? You're not their boss or English teacher!
As long as the correct meaning is conveyed there is not really a problem because that is the point of language - to communicate!
It's actually my job - sometimes it spills over into my social life.
It's actually quite jarring to read things that are not correct. It's impossible not to see them, if your brain works that way.
It's a shame no one cares about getting written words right any more.
Oh wow!
Do you really think you're a rarity on mn?!
You're not!
I've had a few jobs where my role involved proof reading and editing professionally written content.
One of those jobs it was my role to turn very technical writing into plain English that could be understand by consumers for whom English is likely a 2nd or 3rd or more language (That's a challenge!)
Your job shouldn't so prescriptively inform how you behave socially.
It's such a fulfilling career. Experience as production editor, book editor, project editor, proof-reader, sub-editor, copy editor and writer, working for some of the country's major newsstand publications, plus work in an extremely specialised niche area of publishing. I've been freelance for 25 years and love the variety. People ask me back so I guess I'm doing a pretty good job!
What's the opposite of a stealth boast?!
I do it because it's my job.
No that only applies when you are actually working!
Why on earth do people who write/edit for a living feel they have a right to visit their superiority on amateurs who haven't asked for their help?
Not all of us who have done/are doing such jobs do so.