Re: easy way to identify someone who bought something
if you're an idiot to click on "like" (or dislike), whether signed into fb or not, you deserve to be tracked and quartered and those quarters re-packaged and sold an re-sold. If you don't value your privacy, there's nothing to fear!
I think you've missed the point.
You don't have to click on those icons to be tracked by FB, by the mere fact that you are even seeing them means that you are being tracked by them.
And you don't even have to be seeing the icons either, as the article mentions:
Then there's the tracking that advertisers perform on behalf of the news-groomer: “An advertiser can choose to add the Facebook Pixel, some computer code, to their site. This allows us to give advertisers stats about how many people are responding to their ads — even if they saw the ad on a different device — without us sharing anyone’s personal information.”
Facebook Pixel is a single pixel image/icon, usually transparent, so you are unlikely to see it at all. A webpage that includes this single pixel image can track you without you even knowing (unless you use one of the numerous browser privacy plugins), as you aren't even seeing a Facebook icon.