Earlier quoted context omitted.
Today's designers, just like kids these days. In reality, most design work these days is shifting to research and usability testing. Any designer who doesn't consider these things is just not a great designer and has much to learn.
Nearest I can figure, all the tuning is based on "engagement", which is a metric of how long a user spends on a thing. That's a useful metric to tune for if you only care about shoving ads at people, but is pretty much exactly the opposite of what you want if you're trying to help people get shit done.
But you are right, it's likely that modern metrics are things such as engagement, and whether the user is doing actions that are high-value for the company, such as sharing content with their social networks.