This reminds me of when I first got SEIII. The first time I researched Point defense cannons I thought "Look at that range, look at that damage. I am going to kick some serious butt now"
Built me a fleet of a dozen or so destroyers loaded with PDC... and nothing else.
The first enemy fleet I ran across had a couple of destroyers with a handful of frigates with measly old Meson BLasters and Anti-proton beams. "Humph, I thought, I don't even need to bother fighting this one in Tactical mode"
Boy was I confused watching all those little blips flying around, and all my little blips kept going out...
That's when I went back and actually read the weapons description. "Only targets seekers" What's a seeker? Boy was I confused.