The thing is, I don't understand if V4V is such a bad idea, doesn't work, and will collapse, why does everyone spend so much time talking about how it won't work as a payment model? Surely you would just not bother because the people implementing it would just not do it anymore. 

The thing about decentralized systems is the modularity with which they are build allow for different models to be tested. The reason why paywalls and V4V are clashing is that one hurts the other and people advocating for either are just partisans. If there's a paywall, V4V gives away content for an ostensibly cheaper price. If there's a V4V model pay walls give people FOMO and draw from charitable payments. You are participating in a culture war.