Dial up and early high speed internet both gave you a public IP address. The expectation you will have multiple internet devices is more recent behind a nat is more recent. And yes I dealt with an XP box that would get compromised before you could download the update.

Windows even included a utility to let people use it as a router on home networks to "share internet connections". https://support.microsoft.com/en-us/help/310563/description-...