That tagging proposal was written in 2014. World of Darkness tagging was updated again in 2015, making that 2014 tagging schema out of date as a reference.
In the 2014 proposal (which I wrote) the idea was:
And yes, the schema was to tag old-world-of-darkness vampire-the-masquerade at the time. Tagging series plus edition isn't something we do for D&D questions, but that's a D&D-specific tagging policy that doesn't extend to any other games, where we will frequently tag with both the series and the edition to aid discoverability according to what makes sense at the time.
Then in 2015, Onyx Path did some rebranding: Old World of Darkness was rebranded to Classic World of Darkness, and New World of Darkness 2e became Chronicles of Darkness. During 2015 we needed to update tagging to reflect this: Changing [new-world-of-darkness-2e] to [chronicles-of-darkness]
I believe Jadasc's proposal was adopted, so now there's:
... and no series tag at all.1 So now world-of-darkness is a game tag you use when asking about the Old/Classic edition, and that second quote in the question saying “Do not use this tag for questions asking about a specific World of Darkness edition” no longer applies.
This means if you're asking about vampire-the-masquerade, which is also an Old/Classic World of Darkness game, you now tag it world-of-darkness vampire-the-masquerade.
(1: Not having a series tag is weird to me, but I'm not a World of Darkness player and maybe it makes perfect sense to those who do play it, and the taxonomy is for them not me.)