It doesnt take too many exocet missles or something newer to make any ship obsolete. Floating targets are sitting ducks in todays world.
Most anti-ship missiles are designed to hit on the waterline or as close to it as possible, right where most battleships were designed to withstand up to 16" shell fire. The pop up and dive missiles have a better change of really hurting a battleship but even then modern anti-missile systems have a good change of taking them out. Our carriers are far more lightly armored but are able to withstand several missile hits.
Now in a few decades when they get real anti-ship lasers the game will change but until then technology still make combat ships effective.