I am openly poly. My wife doesn't identify as poly and I think she may not be. The fact that our relationship is open is not a secret and I'm pretty visible and vocal about it.
That's kind of my personality type. I'm iconoclastic and have no problem being the "initiator".
I will say this though, given that my worldview comes from the "visible" perspective, I don't know how I would avoid it if I wanted to.
If I'm talking to people I'm friendly with and they ask me "Where is your wife", saying "she's on a date" is my honest answer if she is. To me, lying to my friends or even people I am just friendly with is far bigger of an issue to me than the complications of revealing that I'm poly.
When invited over to the home of a friend, how do I explain to them "She's not here tonight" without making them feel blown off if it happens repeatedly without that honesty? Related, how would I shift from "part of the couple" to "an individual" if I couldn't honestly answer how that happens within the couple?
Also, there is the possibility of being seen as "the cheater" or even weirder (and I admit, this comes from a web series on being poly) the oddball cases where two poly folk are being dishonest to the same people (She's my sister!).
I don't see anything wrong with people wanting to keep their personal details close to the vest, but for me, I don't have any concept of how I could be anything BUT visibly poly and still act consistantly with my other values.