Being in love does feel earth-shatteringly special, unimaginably unique, irreplaceable; but the author is right that that’s how everyone in love feels.
I don’t think that cheapens love, or means that my love for my spouse is “less” because others feel symmetrically the same, or even because I could have felt it with someone else, too.
I think that is what it is to be in love: an overwhelming all-consuming feeling of everything being one-of-a-kind and precious and Right. Thank God it’s not impossibly rare, or only possible under the most specific circumstances!
(This is not to say that love is easy or feels like that all the time—it takes a lot of work, but that work feels worth it and important because of how it feels during the moments when it does come effortlessly.)