You are right, but ISPs will tell you that you're not allowed to host servers anyway. Most have it in the AUP.
replyI did port forwarding in 2010 for a Minecraft server. Basically every router supports it.
replyIt wasn't meaningfully more difficult than setting up the server.
You can't do that with CGNAT.
replyMost isps, you can’t do that anymore as you no longer have a publically reachable IPv4 address. It moved the ‘just configure your router’ part to their equipment, as they now use CGNAT.
replyIt’s gotten much worse.