"Real estate is precious on small phone screens, and users demand that every pixel be spent on something relevant. People are willing to make an exception for ads on free apps; after all, developers need to pay the bills. But the trending topics tend to spotlight micro-communities that don't overlap much with each other. As an optional means of discovery, they're mildly interesting. Forced upon us, they bombard us with irrelevant data that breaks down our carefully constructed social-networking comfort zones."