I understand the security concerns (and they are many) but why can't my phone, which is almost always on, host and serve my content to the 20 odd people who care?
You can buy a 4G modem and have the same issue.
IPV6 would solve this problem easily, if there weren't so many businesses linked to the IPV4 scarcity.
It's the job of a firewall to prevent routing to private networks.
The issue with IPv4 is that there is a limited amount of addresses so we've had to make do.
With IPv6, every device in the world can have millions of IP addresses which are globally routeable.
However we're only at about 33% of traffic being IPv6 capable. [0]
On the mobile phone side, it's a choice by network providers to prevent routing. More of a security thing than anything else. There is a product class called Mobile Private Network, which offers private networks over mobile to businesses.
My personal hot take for the low uptake of IPv6 is that there's a lot of people in the industry that have the attitude of "I don't need it so nobody else does which informs management"
You can see it when people bring up the low upload speeds and someone says "5mbps is all you need for video conferencing". Ignoring how it's painful to upload videos or other binary data for collaboration.
[0] https://www.google.com/intl/en/ipv6/statistics.html#tab=ipv6...
That "illusion" was pretty damn effective at taking Windows, around '00, from "pwned in minutes, no user action required" to "won't get pwned unless you click the wrong thing".
A smart washing machine is more powerful that a computer from 2000. :P
Let's say you had two routers.
1 with NAT and 1 without.
They both will have a firewall that by default blocks incoming traffic.
So they are functionally equivalent.
IPv6 does not need NAT.