Well anon, we in 4chan tend to forget the original purpose of sage. Unfortunately sage has been abused into a tool for legal trolling in /a/.
You can't start a thread saying "Ichigo - sucky character or suckiest character?" but you certainly CAN sage Bleach threads to hell and prevent Bleach fans from seeing them.
That said, although sage bombing is not allowed, such a rule is hardly ever reinforced.