Goldmark markdown parser is surprisingly good and ast it builds enables all sorts of nice features that would be hard to implement otherwise. As an example, youtube embeds feature wasn't that hard precisely because I didn't have to parse markdown or do any hacks with regular expressions that won't be any good any way in addition to be very fragile.
Ast allows me to
Of course there is a bit about parsing links themselves and adding proper embeds, but it's really easy compared to markdown parsing