In my point of view and based on my gameplay, you can still profit from destroying troops. As long as you choose what target you will attack. There are instances that you can perform attacks and don't even take loses. Some targets don't have range units which will enable you to wipe them out using your balanced troops, gaining both resources and some futures if you are lucky.

In my gameplay, I always balance the gains and losses. If I think I have to sacrifice some from my troops like destroying inactive accounts, because eventually they will become my feeders, then I will go for it. It is just a matter of perspective on how to deal with this game.

With regards to the rewards, I think it is kinda frustrating but somehow still hoping for the best. I am not yet at the edge of quitting. I am still pumping and grinding.

So far I am enjoying it and still looking forward to more updates to the game.