Not just that, though thats true too... it's only harmful to the miners themselves, it's foolish to mine with a centralized pool who could be stealing from you via skimming (or via 'hacking' incidents) but it only harms the miner who chooses to do it.

Stratum continues and cements a historical inertia of conflating pooling for payment (which encourages more small participants by reducing variance) with "selling your vote" on the valid state of the network, creating real centralization which is antithetical to the security model.

There is no technical reason why you can't form your blocks locally, according to your own preference and policy, but pay out the coinbase according to a pool's spec and get credited for that work.

This means that pools create a large centralization risk when there is no need for it to be so to get their benefit.  Indeed, it's arguable that miners can move so they're less of a risk than, say, cloud mining— but in practice miners do not move even when a pool is caught ripping people off (and certantly not quickly).