Allow Me to Demonstrate
You don't have to use them for destruction just because they're called "Destroyers".
These fantastic ships are relatively cheap and quick to build, but they can each carry 100 units of resources. When you start building lots of ships, you'll quickly see that an ongoing supply of resources is absolutely crucial. When you farm them from neighboring inactive planets, it's easy to get the Uranium, but sometimes the Coal is a bit hard to reach.
You will always grab loot in the order of its value, meaning you'll get the Uranium first, then the Copper, then the Ore, and finally the Coal. If you don't have enough carrying capacity in your attacking fleet, you won't collect all the resources, simple as that.
To get the Coal, you need a formidable fleet that can travel quickly and carry the heavy stuff. That's where Destroyers come in.
That was my original price... Wait until you hear the deal I'm offering this time...
Check This Out...
That's me, attacking one of my nearby farms with just 81 Destroyers. Notice that I was able to completely clean out the depots, with over 4000 resources collected. With 100 Destroyers, you can get the full 500 if you find the right farm. I can do this daily on multiple planets, simply because I have lots of battleships.
Here's the Deal of the Day!
100 Destroyers sent anywhere in the galaxy for 300 STEEM (only 1 fleet available)
Remember, while Planets and Resources are the vehicle, ships are the ultimate goal. After all, the Wonder of the Universe is a ship, not a planet. Ships do not get burned like resources, only destroyed if you get into fights with other players. Ships have trade value and loads of utility. Plus, you can produce them endlessly.