I think you missed my point in the beginning of that sentence: 'if only you can mine your own transactions'. That changes quite a lot of things; eradicating pools for one.

POW is permissionless even if mining is centralising. Example: turn all mining equipment in the world into a unicorn - will the chain recover? The answer is yes, because regular non professional miners will take over again; granted it will take a long time to produce a block, but eventually it will recover.