True, it's a bit something, what to call it, "not nice" to tell people what to do like that.
But there is still a point in letting them know that people like you exist, that there are people who would like to make a bug report but who are reluctant to do it because it requires using Github.
I think many people think Github is all that exists, that everyone is using Github and that there is no problem with that. (Which of course is exactly the attitude Microsoft wants to see.)