Essential infrastructure describes "assets that are essential for the functioning of a society and economy" [1]. Not things that can cause a lot of damage. Bombers aren't essential infrastructure. Facebook is non-essential.
Nuclear missiles themselves aren't critical infrastructure, but you better bet the launch systems, and specifically the security of those systems, are utterly critical to society's continued functioning as we know it.
As that comes into place and use, how many companies are going to be basing their pricing -- their entire product offers, in light of the availability of this information, this "score" (and all the categorization behind it) -- upon it?
Bingo. Critical infrastructure. (Like it or not, for some of us.)
Edit: people take my comment to mean it won't be a big deal. It will be. However, not on the same scale of taking out the power grid, or the water system, which would lead to hundreds or thousands of deaths. Facebook is not critical infrastructure.
With that said, is it perhaps possible that some people might view this as subtly distinct from power plants, hospitals, roads, and ISPs? Those are what are generally considered "critical infrastructure".
[0] https://science.ksc.nasa.gov/shuttle/missions/51-l/docs/roge...
FWIW though, investors can be fooled.
If you destroy Facebook, Google+ gets some more users.
I understand the point that you don't need facebook the way you need the ability to feed the people in the cities (and thus need roads and power plants). If facebook disappears, life will go on. But as long as it exists, control of it is critical like control over power plants.
In the sense that it's an immediate need for the continued basic functioning of the state, it's possible that there may be some distinctions that could be drawn. Some might opine that these are the distinctions that matter for the designation of what is and isn't critical infrastructure.