Yes, it is not as decentralised as you have thought. I thought this is a fairly known fact. If you need something truly decentralized, I2P is probably the way.
So how does I2P work, I vaguely remember something about it like slowly building a network as you keep your own connection on, and that the architecture makes it much better for torrenting. Is it worth looking into and learning about or is it just slow bad internet?
Traffic is flowing through computers of volunteers, that part is indeed decentralized, but your client needs to find them, and that happens through a centralized service, through a "directory authory" if I'm not mistaken