[im3w1l]

I think it's way more complicated than that. Like you could measure how much better someone feels after seeing cute animals. Short term happiness isn't the only goal and needs to be traded of with other things, both as informing the user about what their friends are doing (you probably do want to know if they get cancer even if learning about it is sad), trending topics so you are clued into what everyone else is talking about, and of course ads. Learning more about the numbers allows better tradeoffs.

[pseudalopex]

The impact of missing important personal news isn't quantifiable in practice. Different people want different things from the platform too. And Facebook can't put everything people care about into the equation as long as the real goal remains getting them to look at more ads.