I'm confused, are you saying that the operators of walled-gardens and app-stores are not middlemen?
And now we have moved in a totally different direction, where all the would-be-small-middlemen and their functions have been absorbed into a couple of giant data warehouses/web properties. That's about as far away from the 'peer-to-peer' nature of the internet as you could be. Firewalls were also a huge nail in the coffin, the fact that to be able to securely connect a computer to the net at a consumer level your best bet is to make it a device that does not allow connections from the outside in.