Wrong. Look at any dictionary. Etc is completely fine. What next, are you going to pretend you write N.A.S.A. or Mr. White? Come on
https://www.merriam-webster.com/dictionary/etc even redirects to the correct URL with a "."
This is all stuff you learn in school. Punctuation isn't obscure or niche. You may not have learnt about semicolons or em dashes in school but you should have and I did. As did anyone that has ever read a novel. There are two semicolons on the first page of the first Harry Potter book, a novel read by approximately every child of my generation. There are loads of examples of the proper use of dashes and other "obscure" punctuation marks in any professionally typeset text.
I was raised and educated in Africa, specifically the GCSE curriculum. I was taught to use etc.
As opposed to what, exactly?