A tax on business.
So I pay an employee $24/hour. He/she spends 6 mins of it on Facebook - an underestimate?
So I'm being taxed $2.4/hour by Facebook. Employee cost is approx 2 x salary so it round terms it is $5. I, and all other employers, have hike my prices to compensate so in reality the consumer pays (or the stockholder if I take the hit).
Given that Facebook has taken 10% of my employee's productivity - then I need to employ an extra 10% of staff to get the same job done. Of course 1% of this would be re-taken by Facebook and so on.
I could filter Facebook on the LAN. But folks would just FB on their mobiles in the bog. So I have no option to let Facebook create more employment at my expense through the addictive power of their exploitative activity.
Well I suppose its good that I and other employers should feel honoured we are paying for a greater contribution to society than Portugal. Thank you FB.