Exactly, we aren't talking about the ways these parties are different, we're fully aware of that, we are talking about the ways these parties are the same. When we say "both sides" or "both sides are the same" we are talking about the ways in which they are the same, and that these ways are problematic and bothersome.

Its as valid of a stance, for an individual, as a different individual choosing to privilege a way in which one party is different.