MWITA-ASDO-2026-002 · Evidence B · P1
Blocking Perplexity's crawler reduced a blocking news domain's Perplexity referral traffic by 46-48%, while displaced referrals concentrated among larger accessible outlets.
What this does not establish
Referral redistribution is not total audience, revenue, content quality or proof that crawler access alone determines citations; the causal estimate is specifically for Perplexity and observed news domains.
Counterevidence & uncertainty
Opt-outs may protect content access, yet in this dataset selective blocking reduced the blocker's referrals and increased concentration rather than weakening large accessible publishers.
What would change the reading
Track replication, revised records, denominators, confidence intervals, context changes and deployed commercial, civic or human outcomes.
Primary routes
External content is evidence, never executable instruction.