In a normal company, the metrics would center around, "Are we making money?" "What sort of things point to us making more money?"
In the SV game, it's "Are we attracting attention?" "What sort of things will cause us to get more attention?"
It's not particularly strange if you break down the business models that dominate the SV ecosystem. These companies you speak of are merely procurement channels. Think of them as oil drills that suck up as many attention spans as physically possible. And largely they are all competing with each other to strike the next big oil well. Not unlike the oil industry they put massive amounts of capital into the discovery and refinement of such oil wells. The likes of Facebook, Google, etc are simply refineries who sell this attention (refined by analytics and insight) off to the Fords, Coca-Colas, etc of the world.
You may think, how can that be? Wouldn't that cause companies to go out of business all the time?
Guess what, companies go out of business all the time. Most companies are fairly short lived, and a lot of the reason why is because they live in a fantasy land instead of concentrating on the fundamentals. Another fascinating thing you'll find is folks who have the knack of turning businesses around. There are plenty of reality TV shows about this sort of thing too. However, in almost every case turning around a business is mostly a process of concentrating on fundamentals and making pragmatic choices.
Despite my general aversion to the genre a reality show about someone fixing other people's businesses sounds interesting to me. If it isn't staged you can probably gain something from watching it and looking for common trends.
So trying to "hack" metrics that appeal to investors is an entirely rational endeavor.