Ok, so this centralised node gets to route my transaction. Because of onion routing he only get the information important for routing, so he only knows which node it comes from, how many sats and which node he passes it on to. He doesn't know who the initial sender and receiver is. What is he going to do to me?
Exactly, all he CAN do is choosing to route or to sensor. Guess what, If he start censoring he becomes a very unreliable node to route through, so he will lose its dominant position.
Your argument is comparable to people who think we would see all these evil monopolies in a stateless society. This is simply not how it works. Without state coercion monopolies can be exelent and remain, or abuse their position and be disrupted.