This is due to cards such as Athreos, God of Passage, but more importantly, were gaining Mana Confluence
This isn't a bad thing, just something to keep in mind, and when teaching a new player this might not be the deck I reach for
Edit: Reread the blog post again, and it seems like theyre saying there are unique ones in the promotional ones that are not in the set
For more info on how this works, see the infographic below
Also, this list was written after the release of the first BW set, so if you stumble upon this list way later and are confused about an errata or something, that may be why
Cards like Archmage Emeritus and Wavebreak Hippocamp dont outright win, but turning your efficient one-for-one into an efficient two-for-one breaks things in your favor