The ISPs would be happy if all their customers pay £20+ a month to check our emails one a week like it was the 1990s, we have heard it all before with the offering 'unlimited' data and then suddenly throttling users because they went over their limits.
This is the alternative. If content providers won't pay for the capacity they use, then users will. Netflix etc will happily charge their users a premium for 4K content, but pay virtually nothing for the delivery of those extra pixels. The latest CoD will charge users £80 and maybe a monthly sub to play FPS games, but pay virtually nothing to make sure their customers get a lag-free experience.
That's kind of the technical argument, ie not all content is created equal, and QoS or CoS could benefit real-time apps so they work well when there's congestion, and packet loss. As traffic levels continue to increase, so will congestion. The only solution to this is to throw money at the problem to increase capacity. This is very expensive, especially when you have to jump tech levels, ie something with a 10Gbps interface costs a lot less than something that can support 100Gbps, especially at peering locations where you have to route and want Nx100Gbps interfaces with multiple peers, transit providers or CDNs.
And then the bigger problem is the constant need to upgrade the rest of the ISP's network, so all the backbone/backhaul links and capacity to the edge switches that form the access network. Content drives those costs, so if content providers won't contribute to them, the only people who can be charged are the users. So expect an end to 'unlimited' offers, and a transition to mobile-style xGB a month tariffs. Users may be unhappy with this switch, especially as they often have no knowledge or control over the apps they run, especially all the garbage that 'requires' an Internet connection and cloudybollocks. You may pay £20/month for your fancy new baby monitor, but it may end up eating all your data allowance and generate overage charges at £1/GB.