Except they aren’t hiding under the radar. The “operation” runs 24/7. If they are botting, when they play doesn’t matter. If Blizzard breaks a bot and does a ban-wave, the time of day they are operating doesn’t matter. The ban-wave looks at the logs. It does not rely on visual confirmation.
I hope you reported this when it was said.
They do monitor it. We’ve been told that they catch a bunch of botting before players even see it.
Banning bots in a whack-a-mole method actually doesn’t work. If Blizzard bans one, the botters just modify their program a little and open another. It only has a minor effect. If Blizzard bans thousands at once, the botters take longer upgrading their software and it is more costly to recreate the thousands of accounts. There is no way to eliminate botting entirely.