I don't think you understand how 'pools' work. Pools are by definition collections of miners who are affiliated by the same aggregator. They are not monolithic bodies, nor do they speak for Bitcoin. They only power they have is providing a canonical representation of a block to miners. The network consensus (the node users) must validate the results.

The pools themselves do not represent an oligarchy, more a federation of miners. Miners are not sticky, and can switch to another pool after a single block is mined.

Miners themselves COULD form oligarchies, however the low margin and continuous ongoing capital expenditure through energy usage prevents this.

Contrast with staking, which will end up being large existing tradfi ('legacy bank') stakeholders, and they will control, censor and centralize the beast.