It causes no end of problems, not just for ISPs and mobile networks but also for people running server networks and for end users like us. I suppose it can be hard to see that when you grew up with the problems and have never used a network where you didn't need to deal with them though.
The world can mostly function without NAT. It's mainly only used to work around address shortages, which aren't an issue on v6, so there's simply no reason to use it most of the time. It can be a useful tool in your toolbox, but it's one that you only need to use very rarely.
Here's a benefit from v6: 40% faster connection setup†. Measurable benefits show that there are benefits. "No need to use NAT" is of course another obvious benefit of v6.
The world can mostly function without NAT. It's mainly only used to work around address shortages, which aren't an issue on v6, so there's simply no reason to use it most of the time. It can be a useful tool in your toolbox, but it's one that you only need to use very rarely.
Here's a benefit from v6: 40% faster connection setup†. Measurable benefits show that there are benefits. "No need to use NAT" is of course another obvious benefit of v6.
†: https://www.zdnet.com/article/apple-tells-app-devs-to-use-ip....