This statement is extremely reductive. You could similarly say that soccer (or football to non-Americans) is simply a matter of scoring. Teamwork? Plays? Defensive concepts? The only thing that matters is scoring more than the enemy, because scoring means you win. This can be true in a reductive sense, however it leaves out the nuance of what happened at what times during the match and what plays occurred dynamically as a result.
In a WoWs sense, it's the equivalent of saying "Just sink the enemy" and then following it up with "I'm good at sinking the enemy, so I'll just go do that a lot." It may function as desired an amount of time, but... Plays? Defensive Concepts? Depth? If you're electing to reduce the game to a damage counter DPS-race then the game isn't a game so much as a background for playing whack-a-mole. I'll grant you that you might not be receiving higher-order teamwork in a Random Battle, but you can still assess the situation around you and determine what is likely to happen and what is the best solution to the "Random Problem" that is being generated on the fly.