So let's take another example: the gene pool of any given species. It's about resilience too.
Not useful enough genes exit the gene pool regularly, does that mean that the gene pool of any given species end up gravitating toward a single gene?
If low bandwitch nodes exit the nood pole that only means we will have a fitter node pool. It doesn't imply anything about the node count.
The issue is with the pace at which an uncontained block size would allow for large entities to capture the network.
Your analogies are all pretty good but they're beside the point.
Following your argument most of the nodes composing the network as we speak would vanish and would quickly turned into a specialized market likely to consolidate into few large entities.