I'm with you.
If you look at history and the kind of surveillance powers governments had compared to the general population, it isn't unreasonable to assume that they can "monitor" everything. In fact you can find several YouTube videos of people who claim they created just such a system after 9/11 for the NSA.
The question is not if the NSA are sweeping every piece of electronic communications, the question is: "how much are they storing?"
If they're just building communications trees then that is a lot less invasive than even automated e-mail scanning. However it is very likely they're looking at content too, because historically (e.g. cold war) they always did keyword/phase monitoring.
If I had to guess, I would guess they're building large communication trees and giving everyone in them a "score" (think: credit score). This score raises based on things like the language used, perceived threat, and similar.
Then when someone's score is high enough or they talk to the "wrong people" you have human analysts who go over their profile with a fine tooth comb...
None of this is impossible with our current technology. In fact it isn't even technically that difficult - just expensive.
Now if you want to get really conspiratorial then let's talk about the public SSL certificate oligopoly. The five or six companies generating the majority of the world's SSL keys are likely handing them straight over to the NSA and in exchange the NSA keeps those companies in power/control of that market.