I've been using MSSQL since the 7.0 days in the 1990s and have never seen nor heard of A) happening. As you said, I'm certain this was "too many cooks in the kitchen."
I didn't have DBA access so I couldn't do much to prove someone had maliciously dropped indexes. It was about an every-other-month occurrence, and it would make our response time go from 200 ms to 90s.