This post only makes the case for em dashes from a writing and expression point of you. But it misses why people now distrust em dashes - it's not about sentence structure or expression, it's the symbol itself.

I have a question to all em dash users reading this - why wouldn't I just use a regular dash in place of the normal full-length character? I have already done this several times in this very comment, and it's a very common convention on the internet. Outside publishing and other types of very high-brow writing, the fifty different variations of dashes with minor differences in length are pretty pointless, in my opinion. There's almost no scenarios where you need to make a distinction between them, what could possibly be misinterpreted because of dash length? So why not just use the regular, standard dash everywhere?