You are seriously under-representing the impact of firewalls on the security of the Internet. Every consumer router has a built-in firewall. They don't need to know anything about it because the default configuration works for most consumers. That's what we should be aiming for as a solution for the IoT security problem. Something that just works for most cases without configuration... much less extensive labeling with commensurate demands of technical knowledge and attention on the part of every consumer.

They are not perfect (nothing is), but a Internet without firewalls would be apocalyptically worse.