Nope. If you get assigned a routable IPv4 IP, you just have a shit ISP. I led the rollout one of the larger O365 implementations. Outlook and the office stack needed like 10-16 ports per user. We served like 150k people with 30 outbound IPs. If you have an IP, you have 64k+ ports to use.

I also deployed it as a pilot on an internal network. Other than getting direct IPv6 connectivity to some services, which sometimes gave us better performance, it conferred no advantage to us.

IPv6 is great for phones where you don't expect any inbound traffic. Even then, every US carrier is using Carrier NAT to route and proxy traffic for their own purposes.

No, they're not. That's other weird policies specific to your ISP.

With IPv4 + NAT, you have a public IP address. That public address goes to your router. Your router can forward any port to any machine on your LAN. I used to run Minecraft servers from a residential connection on IPv4, it was fine. Never had to call the ISP.