Wow. That's so insightful, I think you've single-handedly rendered every research division at every investment bank obsolete. Consider switching careers.
"This company is trading at this price, which is appropriate because this price is what the company is trading at. My recommendation is to purchase shares in this company then sell them at a higher price later on. Alternately, we can short this company's stock, and then profit when the price falls."
This is an article speculating which direction Facebook's stock is going to go in the coming months and years. The efficient-market hypothesis is about as relevant to that as prayer.
I think you are missing the point. The whole conversation about what something should be trading at is stupid. It is worth what it actually trades at. If it wasn't worth the trading price then it wouldn't trade at that price. What it should trade at is always what it trades at so it is foolish to speculate about what the price should be. If enough people will realize that the stock is over-valued, over-hyped and over-priced it will very quickly start trading at the price it "should" trade at.
The GP's comment reminds me of the famous Bill Parcells quote: "You are what your record says you are".
And how does anybody go about realizing that the company is overvalued? The market doesn't work via black magic. People have to think and reason about it.
If I purchase stock in a company one week at $33/share, and the next week that same stock is trading at $23/share, it is highly unlikely that the stock was worth what I paid for it, unless something unforeseeable happened to that company during that week which dropped its value by nearly a third. Market capitalization is only an estimate of real value. The only reason the stock market tends to do such a good job of estimating it, is that so many people are doing their homework before deciding to purchase a share.
Articles like this and discussions like this are critical to a healthy market. They help people decide if they should buy or not, and so they promote market efficiency and accuracy.
The end.