Moreover to the point of streaming 4k UHD movies...why not? You could design the system so that someone who wants to stream a 4k UHD movie just ends up having to pay more for that VPN bandwidth. And network operators will receive more compensation for putting a 4k movie through the web. All the while anonymity is maintained.
My $0.02: I was throwing 4K streaming out there as it's a notorious bandwidth hog. The larger point wasn't to introduce any kind of censorship or limits to the VPN concept itself, but rather to give both providers and consumers a choice.
For example if I was offering VPN services through a connection measured in Gbps then I may very well be prepared to offer VPN services up to 200Mbps either individually or in aggregate (100 x 2Mbps VPNs, 8 x 25Mbps VPNs etc). If I was on 25Mbps cable then I might only want to make 2Mbps of that available for VPNs. Still adequate for general surfing purposes, but if a provider-defined cap doesn't exist then a single 4K stream could saturate my connection.
With both time AND bandwidth components in the proposed marketplace, providers and consumers are both free to decide what they want to offer / receive and the free market will sort out the rest. The end user who wants to surf for an hour can filter for providers offering 1 hour chunks at (e.g.) 5Mbps max and another who wants to stream 4K movies would need to look for providers offering 2-3 hours at 20-25Mbps+. The latter would doubtless pay more than the former.
Ultimately everybody wins in terms of a competitive marketplace and quality of service.