Why does Reddit's AI share seem so low compared to others?

Reddit had the highest scan volume of the five platforms Pangram measured, at 36.7% of scanned items, yet its combined AI share was 4.4%, "one of the lowest" of any platform. The excerpt's explanation is composition. Replies made up 72% of the Reddit items scanned and were "overwhelmingly human-authored (98.1%)," while top-level posts were 11.6% AI-written, close to X/Twitter's 10.0%. Top-level posts were only about a quarter of Reddit items, and the excerpt says they have "far more audience impact." The headline number is low because most of the volume is replies.

The mechanism is weighting. A platform-wide share averages two populations with different AI rates, so a low-rate majority can pull the average well below the rate of the minority that carries the audience. The same split shows up on LinkedIn, more weakly: a top-level post was 1.35 times more likely than a comment to be AI-generated. The excerpt then reports two reversals. On LinkedIn, comments were slightly more likely to be AI than top-level posts once length is controlled, so the apparent format gap reverses when length is held constant. On Reddit, the gap survives length control, and top-level posts still had a 5.25 times greater chance of being AI-generated. Format and length are both in play, and they do not act the same way on the two platforms.

The excerpt also draws a moderation point from the same split. It says Reddit's spam policy removes accounts that use AI to generate spam replies, but this "only catches the lowest-effort spam content." AI-authored top-level posts, which are fewer and have more reach, can "slip past volume-based moderation like rate-limiting." That is Pangram's inference from the composition result; the excerpt reports no enforcement data. Against the nearest notes, Does AI threaten social media's conversational function? locates the structural threat in conversational style, and the reply-versus-post split is the kind of cut that argument needs. But Pangram measured authorship, not style, so the 98.1% human replies do not show that conversation is intact. Why do AI posts get likes without inviting conversation? describes posts that gather likes without the reply-and-counter-reply that produces influence. The excerpt's finding that AI text sits mostly in top-level posts fits that picture in shape, but it measures where AI text sits, not what it earns.

What the excerpt does not establish is how the shares were split by category. It gives the Reddit 4.4% share without a fully-versus-mixed breakdown, and it does not give the sample size for each format. The 5.25 and 1.35 ratios are presented without the underlying reply rates, so the size of the gap in absolute terms cannot be checked from the excerpt. The sample is the same opt-in extension data as the platform figures, so it cannot show that the composition holds beyond that sample. The implication is narrower than the headline: a low aggregate AI share can sit alongside a high AI share in the posts that carry the most weight, and a single platform number hides that split. Whether that pattern holds on reply threads over time is outside what this excerpt measures.