The agent marketplace argument rests on a particular confidence: that distribution infrastructure is the hard problem, and trust will follow from adoption. Six competing platforms launched in February 2026 is not evidence of a mature ecosystem — it is evidence of a land grab. None of these platforms interoperate. The builders who locked into a single ecosystem are already losing ground to those betting on open distribution. The pitch on X — monetize your agent now, the premiere marketplace is waiting — is structurally identical to the early App…