Facebook says it is sensitive to such concerns, and it intends to restrict its intent profiles to broad categories ("soccer enthusiast" rather than "soccer accessories shoppers").
"We’re going to build this so that no single marketer's data will disproportionately represent what we use to improve our ads targeting or ads delivery capabilities. In principle, this means larger marketers won’t disproportionately benefit their competitors," it said in a statement to AdExchanger.
Additionally, website owners will be able to opt out of having data generated from their websites or mobile apps used for purposes of ads targeting. However, if they do so, they lose access to other marketers' Web and app interest data.
In other words, if you want access to Facebook's full arsenal of ad-targeting tools, you have to pay with your site and app data.
History suggests Facebook will keep the targeting broad, according to Marc Grabowski, entrepreneur-in-residence at Highland Capital Partners and a former senior executive at Nanigans and Yahoo.
"There is a decade of precedence with publishers anonymizing and aggregating data sets for category targeting purposes," Grabowski said. "Publishers frequently use category-specific click data to inform behavioral targeting audiences, but less frequently leverage advertiser website landing-page data, as that can be considered crossing the line of data ownership."
The extent to which site owners with valuable data will go with the flow, or ask to be removed from Facebook's program, may depend on the nature of each advertiser and its strategic considerations.
Jewelry retailer Alex and Ani is one advertiser that will participate.
"The value of what we're getting outweighs the risk of giving up data to a competitive set," said Ryan Bonifacino, VP of digital strategy for the brand. Informing competitor campaigns is not a large concern, he said. "We assume that very forward-thinking sophisticated organizations can get our (shopper data) anyway. The Sephoras of the world have the ability to target Alex and Ani customers if they want to."
Bonifacino does have a gripe for Facebook about the new program: "My major issue is a lack of education not only with our brand but with every other customer."
Alex and Ani's comfort with Facebook intent targeting can be partly attributed to the relatively short consideration cycle for the casual jewelry it sells. Marketers in the automotive, travel and financial categories are likely to fret more.
"This is great for brands who may not have a deep first-party data asset as they will be able to benefit from data gathered on vertically relevant sites and apps," said Grabowski of Highland Capital Partners. "This will become especially interesting if category specific desktop website data can be leveraged to target audiences using mobile devices."