eth is not cenralized and bitcoin isnt too,
its pools do not own the hardware connected to it and have no power to use it for their own purposes

once smb has detected that the pool he uses is doing something wrong - immediately he reports to community and the miners will start a mass disconnect
and it will be extremely hard for such a stupid pool to restore confidence , i would say impossible, that's why it never happened

so dont be afraid of all these pictures with pies of a hashrate distribution - they are not an evidence of centralization, people who post them have zero understanding of how pools work