Why he belongs here
Pinker is useful less as a source of conclusions than as a reminder to ask for denominators, baselines and historical comparison. A dramatic anecdote can be true while the trend moves in the opposite direction.
His public arguments about social media are especially useful because they complicate the easy story. Humans were irrational, conspiratorial and tribal long before recommendation algorithms. That does not make platform effects harmless. It makes causal claims harder.
Keep the friction
Pinker attracts substantial criticism, including arguments about how he selects indicators and frames progress. That friction belongs in the reading process. The point of a thinker page is not to manufacture a saint. It is to identify tools worth carrying and claims worth testing.