[2022] Ok stop this, stop it now!

It's worth remembering that rewards aren't based on Damage in a number-sense. Rewards (Credits/Base XP) are doled out based on %health done. Half the health on a DD is worth the same as half the health of a BB, even though the BB's healthpool might be 5 times larger.

Submarines are loot pinatas in the same way as Destroyers.

It does, yes. You can learn about how Credits/Base XP is awarded in this video!

You can search "How It Works World of Warships (Topic)" in YouTube, or you can use the in-game section.

From Port, select the Gears in the Top-Left:

Then go to "Video Tutorials":

Then Profit! er... Watch!