No corporate IT would have firewall setup to allow every computer to be routable from the internet.

So practically a globally addressable IP or not makes no impact on ability to be routable publicly

In the 90’s, this set up (public IP everywhere) was very common. I remember working in a couple offices with no firewalls.

90s were a different time for the internet, even till right after dot com bubble being online was relatively safe, many companies would not even have had dedicated InfoSec teams, no audits and compliance processes were covering firewalls etc

I maybe biased, I grew up in the 90's so I dont' really know how it was before, I do hear people reminisce about days before eternal September and bb groups and the good old 80's so perhaps it is always been a downward gradient as more and more people came online.