Well, first of all, you can write. No worries about that. You have what it takes - in non-fiction, anyway.

Secondly, all publications and publishing houses have some sort of style manual. In a newspaper, the subs will fix anything a journalism writes in order to fit the publication standard of the newspaper. In a publishing house, a copy editor will do that.

On Medium, ithe algorithm kicks you off the potential distribution list if you don't follow that formatting, which means they won't distribute your work to a wider audience. Many people want their work to be distributed, so they have to adhere to the rules of the house.

The only rules you need to know for publishing on Medium are on the HELP pages wheere Medium set them out. Nothing more is required.

As for people teaching one to write, if one didn't get it while one was at school, I doubt it's possible in later life. Of course, there are always exceptions.