Does this mean using only the Basic Syntax (John Gruber’s original design)? In my opinion, the basic syntax is not complete. I’d strongly suggest using the extended syntax (https://www.markdownguide.org/extended-syntax).
Will HTML be restricted? From Basic Syntax Markdown Guide (https://www.markdownguide.org/basic-syntax/):
Note: Using Markdown doesn't mean that you can't also use HTML. You can add HTML tags to any Markdown file. This is helpful if you prefer certain HTML tags to Markdown syntax. For example, some people find that it's easier to use HTML tags for images.
I changed from the markdown2 python module back to the default one which seems to be used more often. I think we should stick very closely to the original markdown syntax. I find that one quite loose already and it allows 10 different ways to do the same thing, but this is what people are used to.