A bank operating the platform is a good example. It is certainly possible, and people can and have taken the Ethereum Virtual Machine and ran it as a permission

A bank operating the platform is a good example. It is certainly possible, and people can and have taken the Ethereum Virtual Machine and ran it as a permissioned network. To the extend that we can trust Chase to do it, that would work fine. But to that I would say that the banks haven't built it, and I don't see it happening or gaining adoption. Whatever they build will by definition not be an open network, and will likely not cross too many geographic borders. It is sort of inconceivable that some 16 year olds would be allowed to run a lending protocol on the Chase blockchain, or even a random adult, for that matter. Plenty of people would find that positive, no doubt, but it is even hard to imagine a platform being built where companies in say India could get access to on the same terms as those in the US. Ultimately, the permission-less nature of Ethereum is what has built the DeFi infrastructure we have today, which for all its flaws, is pretty impressive.