AA Traps continue to exist. Halland frequently uses its low Air Detection to light off with AA after planes are close enough to be hard engaged. Islands can be intentionally used in similar ways as well as using smoke to provide AA for a large area while remaining undetected.
While that specific proposal has not been made, I can say that I made a proposal regarding AA being made invulnerable or functionally invulnerable via use of the aforementioned upgrade about a year ago. So, this is a known proposal and it would be cool to see should it ever actually be a thing.
My job is to represent community pain points and destructible AA has been on the list since before I was ever hired.
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