Musk frames read-through completion as a healthier ranking signal than raw engagement, and there's real logic to that — a post people actually finish is harder to fake with outrage bait than a click. But every engagement metric eventually gets Goodharted, and 'time spent' optimization is precisely what turned feeds into slot machines in the first place. The exponential growth claim also deserves a raised eyebrow: self-reported platform metrics from the platform's owner tend to be curated for the narrative. What's genuinely notable is that X's recommender now runs on xAI-built models, turning the social network into a live deployment and feedback loop for Grok. Few companies have that closed circuit; whether it yields a better feed or just a stickier one is the open question.