Honda actually does sell crate engines, but they will only sell them to racing teams. You have to be part of their racing line club. They have a crate engine for the second-gen Fit, but even that is restricted to their club (their lineup consists of the 2nd-gen Fit engine, the current CTR engine, the 9th gen Civic Si engine, and an IMSA-spec version of that 9th Si motor).
Why do they do this? What is wrong with selling their crate engines to the public? Several other companies have no trouble doing so. GM has a robust crate engine catalog, but Ford and Chrysler also sell their crate engines to anybody.
It would also be cool if Honda sold a B16 crate engine and the high-rev K20 from the 8th gen Si