It ain't poly if you're just fucking around.
I don't object to people fucking around--more power to 'em! I also know it's not polyamory. People may exhibit a range of behaviors along the spectrum of nonmonogamy. Yes, swingers may become attached in some measure and that may lead to full-blown romantic ties and polyamory. Some folks may swing AND have multiple loving relationships.
That, however, doesn't erase the fundamental divide between swinging and poly. Swinging IS all about the sex, despite some swingers wanting or going on to seek romantic connections. That the people add other behaviors doesn't mean that swinging is something other than what it is. You'd be mistaking the actor for the act to say otherwise.
In disc sports, ultimate and disc golf are two distinct activities. There are ulty players who also golf and golfers who also play ulty. To say that ulty and golf are indistinct because some players engage in both is nonsensical. The same applies in the world of nonmonogamy.
When speaking of various forms of non-monogamy...it ain't poly if you're just fucking around.
While polyamory, open relationships, and swinging are all distinctly different approaches to non-monogamy, they are not mutually exlusive. Folks can, and some do, engage in more than one of them at a time--and it's all good.