It's true, you can make credits in World of Warships with low damage numbers. The trick is playing the objectives. If you ignore the objectives you are cutting out a good source of credit income.
Not only did I get 1 solo cap and 1 assisted cap, I earned 8 base defense ribbons. That's a form of playing the objectives and it pays well.
Ending up on the top of the winning team when bottom tier is nothing new for the Fiji.
Good gunnery skills helps in all tech tree British cruisers, you don't have high explosive ammunition to mask below average gunnery skills. 262 hits for 465 shells fired is an example of how you can still perform with armor piercing ammunition only.
Don't believe posts on the official forum from players who have not figured out the economic mechanics built into World of Warships. If you only farm damage from big slow ships and never play the objectives you will earn good experience but your credit income will be lacking.