Licensing would be the least work for both end-users and developers if GitHub ran an "Open Software App Store" that accepted pay-licence fees from end-users, and distributed these to developers, both those in the fork and prerequisite trees, and within the packages themselves (based on a registered developer income share). I responded to GitHub's request for suggestions with just this, pointing out that it could earn them, like Apple and Google, income via an app store cut.
The wordiness of the DevWheels licence just formalizes all this app store functionality, so licensing can still proceed if a store isn't available, plus making sure that no store has a monopoly. I think it's better to put the burden of licensing the dev-chain on the developers themselves, rather than requiring end-users to get multiple licences. But the presence of the automated licensing of an app store makes both approaches equivalent.
And yes, some of the detail of the DevWheels Licence is what to do when you can't pay someone in the chain. Again, an OSAS could handle this smoothly, but the licence needs to be clear about what happens when there's no app store. DevWheels chooses to have end-users get licences from the directly-upstream packages when they are unable to get a licence for a package they want to use, with any licence fee increment by this package forfeited, and have developers do the same thing of moving one level up the tree when they're unable to forward a payment.