in order to be able to mine like that and find blocks, you would now need to be at a fairly significant scale. and if that was the case, your incentive would be to find and publish valid blocks so you can claim the block reward and fund your operations
it doesn't rely on people doing some 'right' or noble thing based on some principle of decentralisation. its business and profit motive. if you don't do it someone else will and you'll go out of business fucking around pretending to 'mine' on some tangent 'chain'