[erostrate]

I suspect the author only counts raw material. So players who lose a pawn but gain compensation reduce the perceived impact of losing a pawn. Including many openings where you temporarily give up a pawn (queen's gambit, benko, etc).

[nomilk]

I was thinking the same. It could be true for higher ELO players being down a pawn is a good thing, since your opponent took the bait.