Personally I was taught not to use it, but I quickly realised just how dumb and inconsistent it is to not use the Oxford comma, so I rejected that and now insist on always using it.
I was also taught to put two spaces after a full stop when typing. That's even dumber and I will actively correct it when I'm editing something written by others.
Basically, people need to learn not to take to heart the rules they're taught in primary school as though they're set in stone. Realise that their primary school teachers may have been working on outdated information, may have been teaching a simplified view of the world that's age-appropriate when they taught it but shouldn't be applied rigidly at a higher level, may have taught something that has since become outdated**,** or may have been straight-up wrong.