Because frats are not a put upon minority, or any segment of society that deserves our contrition and respect. They're drunken twenty-something white guys whose primary concern is how to be drunker and whiter and twenty-somethinger. They are an outgrowth of an otherwise useful function (university), not useful in and of themselves.

The reddit post is applicable because it is a rejoinder to those who claim offense at that which cannot reasonably be claimed to cause real offense to those for whom such a thing matters.

How do you not see the irony here?

"They're drunken twenty-something white guys whose primary concern is..." <--- Stereotyping. Generalizations. Right here. In your comment.

There are fraternities and sororities whose members are not all "twenty-something white guys" and whose efforts are worthwhile. Do a smattering of research and you'll discover this.