There's more to the internet than just port 80, so to declare that a scan encompassing only a single port on each host is a scan of "the entire internet" is somewhat mistaken.
The more correct title would be, "a scan of the entire World Wide Web."
The more correct title would be, "a scan of the entire World Wide Web."
More correct would be "A scan of world wide web servers running on the default port 80"
"We experimentally showed that ZMap is capable of scanning the public IPv4 address space on a single port in under 45 minutes, at 97% of the theoretical maximum speed for gigabit Ethernet and with an estimated 98% coverage of publicly available hosts."
Why be in doubt when the research is published?
Did you even read the documents?
This makes "they visited the whole internet" true, "they aren't limited to web only" also true.