Andreessen Horowitz partners Olivia Moore and Justine Moore published an essay titled "Welcome to the B2A Economy" on a16z News on November 11, 2026, arguing that AI agents are becoming the web's primary users. "For years, retailers and platforms built walls to keep bots out - now, they will have to fight for bots' business," they wrote. a16z says it is the first in a series, with pieces planned on consumer agent usage, how agents choose sites and products, agent infrastructure and remaining hurdles to transactions.
The essay cites HUMAN Security data showing agentic browser traffic grew 8x between August and October, counting allowed and blocked requests on HUMAN customer sites. Meta's Muse had the largest share (60% in the essay text, 59% in its chart, PPC Land notes) and OpenAI products a combined 30%. An Adobe and J.P. Morgan chart shows AI-referred traffic with 53% higher revenue per visit in July 2026, while its year-over-year growth fell from 269% in March to 62% in July.
PPC Land reported that several claims run ahead of the essay's own charts: the majority-of-traffic claim rests on a chart of all bots, at 51% in 2024 and 2025, and the code claim has no source. The essay says most enterprises still block agents, without a figure; PPC Land points to DataDome finding 2.4% of 21,491 sites stopped all ten of its test bots, and Blend finding 29 of 200 retailers refused its shopping agent. The newsletter's disclaimer says a16z has not independently verified third-party data.