While they might be minor, there are definite advantages to spying, such as knowing the opponent’s war teams up to 24 hours before the war starts (assuming there’s a reason why we can’t see the opposing teams on the battlefield beforehand). If you use group chat for strategy planning, they’re privy to all of that, too.
I found another thread on this from last year. Mods, feel free to merge if you want (as long as I don’t lose my “Nice Topic” badge as a result 
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