Disagree.

Effectively speaking, the 'benefit' of a harem is that you can have a relationship with any (or maybe even all) of the girls involved. In a case of a show like SAO, then benefit isn't open (since Asuna has actual standards) nor would Kirito want to take it even if it were.

To take an example from a related concept: love triangles

[Mild Kaguya-sama manga spoilers](/s "We see later on in the manga that a certain semi-major character aside from Kaguya has feelings for Shirogane. Now, that's two girls (Kaguya and this girl) liking one guy. So if we're going by the common definition of a love triangle, then it fits. But ask any manga reader whether they'd consider it a love triangle, and they'd say no. Because it's clear that this girl is not endgame. They know that if Shirogane's gonna end up with someone, it's infinitely more likely to be Kaguya, and the manga never shows him having any feelings for this girl in the first place")