Employee-built AI agents caught on, but suite vendors are taking the money — resolves 2026-12-31

The debate: in late 2024 startups such as Dust and Lindy bet on horizontal platforms that let non-engineers across a company build their own AI agents, instead of tools built for one job function.

Why it matters: it decides who gets the enterprise AI budget, the suite vendors that own the screen employees open every day, such as Microsoft and Google, or the independent build-your-own platforms.

Who is on each side: founders of independent platforms bet that horizontal tools would take over whole companies; SecondSource reads the adoption as real but the payoff as landing mostly with the suite vendors.

SecondSource’s reading: letting employees build their own agents has worked, but the suite vendors are the ones getting paid. Microsoft has 30 million paid M365 Copilot seats, Google's Gemini Enterprise has 8 million seats across 2,800 companies, and Glean, one of the larger independent platforms, has annual recurring revenue of about $300 million.

In Menlo Ventures' 2025 annual report on generative AI in the enterprise, “horizontal AI” (general-purpose tools used across every function) drew $8.4 billion, of which assistants bundled into suites took $7.2 billion and “agent platforms” only $750 million, about 10%, a figure that even includes Salesforce's Agentforce.

Our bet: in Menlo's 2026 report, agent platforms will still be under 25% of horizontal AI spending. The 25% line is our own, set well above last year's 10% so that a real structural shift can be told apart from survey noise.

The original material behind this call has not yet been linked here in a form readers can open and check.

Settled when Menlo Ventures publishes its 2026 State of Generative AI in the Enterprise; within a 30-day grace period, read the agent-platform share in the report's horizontal AI section.

What would overturn it

If agent platforms reach 25% or more of horizontal AI spending, platforms that let employees build their own agents have become one of the main lines of horizontal spending, and sections two and seven of the report, which say the money mostly flows to assistants bundled into software suites, need to be rewritten.