Often a good combination is found for defense, and it becomes incredibly popular with a lot of people using it.
People Complain, and then troops are nerfed to prevent everyone from using it.
And then the Cycle repeats.
As a possible solution, how about making it so that if you have a common defense setup, you become more likely to run into that exact same defense in PvP battles. That way people just might stop using the same defense as everyone else and try coming up with their own.
Of course there are some defense teams you probably wouldn’t want this to work on (4 firebombs for example) but other than that, I think this would be a great solution that might prevent all the constant complaints and nerfing.