Naturally, anyone would be willing to achieve multihoming benefits,
but usually the associated costs, e.g. caused by obtaining physical
connectivity to two ISPs, do not justify it.
This is a argument that begs the question "is it expensive". You are
assuming that the answer is yes, but it's not with a CWN, one of the
main points of a CWN is to share bandwidth from people connected to
different ISPs. That's different people, each individually connected to
one ISP, but sharing the traffic between them, in a mesh, or a managed
network, whatever, they are still sharing it.