What is the worst chess opening/defense?
At a higher level than I play at, for sure. But at around 1700-1800, the Modern transposing into KID type structures has served me well (with a couple of self-destructions thrown in for good measure!). But generally, it's resulted in very solid positions as black. It's certainly far less easy to go wrong than with the Caro Kann or any of the swathes of different Sicilian variations.
Yes you are right, however, the saemisch and some of the classical times are very theoretical and general principles don't matter very much