wrt esni the anonymity pool is definitely the set of content that can share the same address pool. In a world with lots of CDNS (and several multi-CDN switching services) this covers a huge amount of content - but I agree - not everything.
If you think about the best/worst case scenario, would you be happy if one CDN would deliver everything? I think that we would be in a worst situation... ideally, I think that everyone would have their own servers and that your ISP would not even be able to see which IP addresses you are talking too (completely decentralized)