I understand GitHub is in desperation to go beyond programmers, but this is a ridiculous expansion goal!
Probably because of the needless profanity and lack of an explanation for your statement (my best guess, I did not downvote you).
> bells and whistles
These kind of features are completely unnecessary for developers, but are useful for the less tech-savvy team members. The markup is not hidden, so it provides a way to learn some basic MarkDown (good!). That in turn improves communication, which improves your product.
Beware of the fallacy of believing that because someone finds the time to polish their product or add seemingly simple features, they don't invest resources in more complex features or research and development. These are not mutually exclusive goals, even though resources are by definition limited.
There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy.
Yes, you might call it "bells and whistles" or "polish", but that polish is one of the reasons that GitHub is where it is (instead of Bitbucket, despite Bitbucket having the better free offering etc). They've gotten were they are by being easy to get started.