The issue is more complex than just a bigger pipe.
As a site owner, you pay a service provider (or cloud hosting service or whatever) to offer you a certain amount of bandwidth to host your site.
The problem comes when other ISP's implement their fast lanes and traffic from your site doesn't get equal priority to traffic from another site who has paid that specific ISP to prioritise their traffic when serving their customers.
So you end up having to pay multiple ISP's to prioritise your traffic on their networks. Your site could appear slow even if you've paid your own service provider for a high bandwidth.