Interesting that in the title, stated in absolute terms in the text, and from the designers they interviewed, they cite getting lost as crucial for the genre. Personally, I disagree. Getting lost has tended to be why I didn’t care for certain games in this genre, like Axiom Verge, and it soured my otherwise higher opinion of games like Hollow Knight and Symphony of the Night. Still, I think this is a good exploration of the genre and what makes it tick.
I would argue that 2D platformer should be part of the definition.
Then you’d be excluding the Metroid Prime games from the genre, which doesn’t make a lot of sense.