I agree and also feel like if you write your readme file in a way where it wouldn't be usable in a text editor by someone who merely cloned your repository or downloaded your tarball, you are simultaneously misunderstanding the point of a readme file and the point of markdown... what you want is a website :/.
(That said, this article is about your "profile", which I have never used myself, never look at from other people, and I guess don't care what other people want to put on theirs? ;P)