It all comes down to war. Agriculture is important because when your country will be at war with another country, you might not be able to trade food. So if you can't grow your own food, you're lost. So it's important to keep some farms in your country to be able to scale if necessary.

IT was not as important until recently. At this point some things are almost as important as food. If your military infrastructure depends on some network equipment, you need to think what will happen when you'll be at war with a country that makes that equipment.

Of course it's not possible to build all equipment from sand to CPU in the country, unless that's a huge country like Russia or China. So there will be compromises. That's not the case for the food, though.

Facebook is not important. If US will be in war with EU and shuts down Facebook access, nobody will care.