Sure, but it's lust. A primal sexual attraction. A physical thing. You can't have emotional attachment and an emotionally intimate relationship with someone after one night.
Let's be clear on what feelings we mean. Lustful feelings of attraction, sure. It gets more murky when we speak of other feelings of attachment and familiarity.
Hear the other side of this: part of the stigma around polyamory is that it's primarily made up of people with "issues." We're either predatory, vulnerable, emotionally unavailable or plain unstable. So when someone comes in and says that they're blowing up their whole world based on their feelings of lust and some vague belief that they are "poly," it plays into this idea that polyamorists are predominately fickle, reckless and all out destructive to themselves and others.
I find that disrespectful.