"It is a similar concept to export of physical goods into a country/trade block. Either comply with the local regulations on quality or your goods will not be allowed."

That analogy is what I take issue with. It's clear that Facebook, selling ads to European buyers, is doing business there. But is every random web site with a few European users? Does putting up a web site suddenly mean you're doing business in every country in the world, subject to the jurisdiction of all of them simultaneously?

"The US State Department does not really get to have a stated position other than diplomatic."

Diplomacy is what it does, and its diplomatic position on trade issues is relevant.