I agree with this and have posted numerous comments here to that effect, particularly on the value of intent (with respect to the effectiveness of online advertising).
Th attitude of "eyeballs not revenue" and finding that repeatable, scalable formula are almost a religion on HN and in startups. It's generally a strategy I approve of.
Even dropping 20% since the IPO (currently trading at just over $30 as I write this; and bear in mind that even Groupon--at least initially--enjoyed a nice IPO bounce), the company is trading at a huge P/E ratio.
I get why this is: it's speculative. FB is still viewed as a growth company and the speculators feel that there is huge unrealised monetization potential.
I remain a skeptic regarding the value of "social" in advertising. The OP is right: all this data just means--maybe--a slightly higher CTR, at which point Facebook is just another display ad network and that doesn't justify their valuation.
As an aside, IMHO Twitter is in this same "put up or shut up" boat. I don't believe Facebook is doomed (IMHO Twitter is). I just believe the value of the data silo they have is both overstated and transitory (at some point--one way or the other--Facebook won't be the gatekeeper to your profile and social graph).
Facebook has done a lot of things right as a business (the Like button being foremost among those IMHO). Personally I believe their biggest mistake was spurning Apple: Apple wanted to use Facebook for their Ping boondoggle.
Disclaimer: I work for Google in display advertising.