That's ironic. To me, the implication of browsing LinkedIn at work is that you're looking for another job. Whereas if you're browsing Facebook or Instagram you're just wasting time.
That's how I've seen it, definitely. At my old job it was at the point where you could tell who was pissed off at what time by seeing who'd been working on their LinkedIn profile... and after a company-wide announcement, everyone would update within a day or two.