If what you wrote were logical, then decentralization would always be the same as centralization.
Decentralization is where the decision making power is spread out to as many actors as possible. A few miners in China making the decisions for all the users of Bitcoin, is not decentralization. You are conceptually conflating the sham of representative democracy (or in this case
taxation without representation because we don't even get the illusion of voting) with decentralization.
I recall those days when GHash.io was controlling 51% and people were saying that it's not decentralization, because miners will leave the pool should it abuse its power. Are you sure it's few
miners making decisions, not few
pool operators?
As I explained upthread, moving between pools doesn't necessarily enable decentralization, because marginal cost of mining will dictate that miners MUST seek out a pool with significant portion of the system PoW hashrate, otherwise the miner will be unprofitable. For the professional miners not at the margins of profitability, they are already centralization.
Even the Chinese claim their mining is highly concentrated by pools not by each miner, and observe how the Chinese government was able to force those pools to adopt a policy of not supporting a block chain increase.