Tiktok optimises for what people spend a long time looking at, but I don’t think that anyone would claim the metric it uses is what we would want to define as quality in the broader sense.
I seriously wonder if Tiktok uses eye gaze tracking in their interest assessments. If people's eyes follow the same gaze pattern on a clip repeatedly, that's a damn clear indicator of interest.
My personal hypothesis (based on nothing) is that TikTok just uses the very strong signal of watch time. If you watch a clip all the way, or multiple times, that's good. If you skip early - that's bad.
When I had Netflix I remember being frustrated that Netflix would recommend me shows "based on" content I had watched for a few minutes, decided I didn't like, and backed out of. Why would you recommend me content if you have a strong signal I dislike it?
