[rohan1024]

The original purpose of NAT was to get additional devices connected to Internet since we had shortage of Ipv4 addresses. For security, we have firewalls. If we had not been dependent on NAT for security, firewalls would have been actually configured. We will have to configure firewalls with ipv6 anyway.

[dboreham]

NAT arose long before any address shortage concerns. Rather it was a response to ISPs attempting to charge "per user" by associating a fee with each additional address (note this is long before residential ISP service we know today: Internet service was for businesses with retail subs only having ppp access via dialup). NAT allowed customers to work around the ISPs pricing model at the time.

[phate]

When my family first got broadband via Comcast@home back in the early 2000s they had a proviso saying if you wanted more then one computer required a separate subscription. My dad and my bother quickly figured out we could get around this by using Windows Internet Connection Sharing. We eventually got a Linksys Router that did the same job and was faster. IIRC even most dial up ISPs did the same thing, if you wanted more then one computer online you had to use separate creds.