Actually with a smaller turret it would be workable. It's not the concept,
but the size that makes it silly.
Did you read the title of the topic!
Are you going to invade a country from the beaches, you going to need artillery support. This 8" armed artillery ship are the perfect solution, and to backup the 8" gun we also have an twin 3" gun.
Notice that there are mounted rocket launcher on the bridge wing, but to make it more easy to aim those rockets, the entire bridge can rotate.