Being an endpoint that is closer to the user is not the same as being a route between that endpoint (or any other endpoint) and the user.

> CDN nodes should be understood as caching routers.

In some respects, yes. But in other important respects, no. For example, CDN nodes do not route traffic that does not have that node as either a source or a destination. The fact that the content at that node ultimately comes from another source does not change that; it simply means that some of the traffic to and from the CDN node is to and from the ultimate source of the content. It's still not at all the same as routing traffic to and from arbitrary endpoints.

> Being closer to the user – the CDN’s value – rests in having a better position vis-à-vis the last-mile network. A better position vis-à-vis the last-mile network is what Netflix bought.

You're conflating two different ways of taking a "position" in the network. A CDN takes advantage of the existing network and the existing routes to place copies of content closer to users. It can only use the existing "positions" in the network, not create new ones.

The Netflix deal created a new privileged route that didn't exist before, for Netflix content going to Comcast users only. So the "position" Netflix traffic is now in with respect to Comcast users didn't even exist before the deal.