51% attacks are attacks on the blockchain. It prevents legitimate blocks from being effective.
6% attacks are attacks on the technology developments. It prevents legitimate soft-forks from being effective.
51% attacks are well known by Bitcoiners. Fortunately it's not happening. However, 6% attacks have been going on for a while and there is no sign it will stop by itself. It's time to address 6% attacks.
UASF to the rescue.