Very few people would agree regarding Yelp. Almost no financial analyst worth a lick would use trailing revenue (instead of net earnings) as a way towards finding value in a company.
Maybe I am missing why Sam points Yelp out at all here...
Trailing revenue makes more sense than net earnings when a company has proven profitable unit economics but hasn't yet saturated its market. At this point, it always makes sense for the company to reinvest any profits into additional sales & marketing rather than bank it, because it earns a predictable return on capital > the market as a whole. A company in this stage will show zero or negative earnings during the entire growth phase (see eg. Amazon.com), but future DCF will increase in proportion to CLV of the whole customer base. Assuming stable CLV, trailing revenues is a pretty good proxy for this metric.
Yelp seems like a fairly good candidate for a business at this stage; its unit economics are probably known to Sam, but it's doubtful that it's saturated all local businesses out there.
I think Wall Street is now learning away from treating Yelp as a high growth company. The question they are asking themselves is whether Yelp is reinvesting profits or if Yelp just can't be profitable.
Yelps business is a competitive one. Their main revenue generation is selling ad space to local businesses. They are a yellow pages of the internet.
User growth is slowing. I'd fear that Yelp just can't grow past any profitability issues. There is only so much money you can make from advertising.
Saturating Yelp's target market is labour-intensive work though, with high churn inevitable due to the nature of their customer base. Selling and renewing classifieds to a mass of small business is costly. Sure, you can eke out more profit even if your costs scale proportionately to revenues, but there's good reason to believe the CLV will actually decline and acquisition costs rise as they aim for higher saturation. With their brand and reach well-established for some time, it's the restauranteurs who aren't digital marketing-savvy (or think Google offers better ROI...) they're now looking to sign up.
Maybe I am missing why Sam points Yelp out at all here...