Parens and em-dashes do different things. A simple parenthetical is an secondary aside (it's a half step towards a footnote). An interrupting phrase is intended to (abruptly) command attention.

I mean, make the case em-dashes are overused and used lazily, I'm right there with you. I just don't see the pretense.

I understand that, I'm saying that people mis-use them when they mean to use an em-dash. I think I ass-u-me'd a bit too much in my comment.