Even with normal NAT, you have to set up the port-forwarding, and you have to know how to do that.

Also, some routers have a bug¹ whereby even a properly port-forwarded service won't be accessible from within the network. E.g., the port-forwarded service "works", except for you, on your own network. Really frustrating since it means how you connect depends on where you are, and it's a lot of special crap needed to determine "oh, okay, I'm on the home network so use the internal IP"; almost ended up setting up a split-horizon DNS to deal with it².

¹ISPs will tell you that they "lack a feature". Yeah, okay.

²but then we moved and now we have a different monopoly for an ISP.