Probably they mean to convey significant digits, though I feel it's safe to assume people would read "1300" as an approximation, not pointing to the year 726. I found it odd too.
Edit: "The newly-discovered manuscript in the National Central Library of Rome of Caedmon’s Hymn dates from between the years 800 and 830, making it the third oldest surviving text of the poem." So... 1.2k then?
I'm curious about this too. I thought saying "we in Holland" was equivalent to "we in England" rather than "we in the UK". Is it acceptable in the Netherlands? (Or maybe just in Holland proper?)
Optinal tags have always been allowed in HTML, for the simple if debatable reason (hence xhtml) that some humans still author documents by hand, knowingly skip md et al _and_ want to write as few characters as possible (I do!).
This is clear in Tim Berners-Lee's seminal, pre-Netscape "HTML Tags" document [0], through HTML 4 [4] and (as you point out) through the current living standard [5].
I agree, modern definitions exclude 1 since "we lose" unique factorization. It's interesting to note [1] that this viewpoint solidified only in the last century.
Panel 1
Waiter: "Sir, I’d like to ask you to take off your cap in this restaurant."
Smurf: "Take off my cap? You’re not asking me to take off my pants, are you?!"
Panel 2
Waiter: "That’s not the same."
Smurf: "That is the same."
Panel 3
Cook (to waiter): "Let him put his cap back on."
Waiter: "That’s maybe better."