[organsnyder]

Home computers weren't normally networked, but enterprise computers (such as the Walmart example given) absolutely were.

[happyopossum]

They weren’t connected to the internet though, and there weren’t state sponsored hackers on the other side of the world that could access them.

[icedchai]

Many enterprise computers were connected to phone lines. A few were connected to global X.25 networks like Telenet/Tymnet. Some were even on the early Internet. True, they were unlikely to be DOS systems, but plenty of DOS systems also doubled as terminals.