This is an interesting question.

One would think, since OpenBSD is BSD licensed, it would be more likely to have vendorized forks available on the marketplace. Companies being obliged to share their code is allegedly a disadvantage of GPL-licenced Linux. But with OpenBSD, there are no prominent commercial forks. The one "active" OpenBSD fork today is HyperbolaBSD, and it hasn't made a single release yet after 2 years. Previous attempts at OpenBSD forks have failed (Bitrig, ÆrieBSD). Somehow, OpenBSD appears to be less fork-able than other BSDs.

Why does the OpenBSD project subvert our expectations of a BSD-licenced OS?

I'm asking as someone who had a positive experience setting up an OpenBSD router and VPN, but not much beyond that.

I don't know of any big ones that are still going. OPNSense runs on HardenedBSD (a FreeBSD fork) and is excellent. FreeBSD and/or NetBSD is/was used by Juniper, Sandvine, Dell (Force10).

I think the main blocker for OpenBSD in the commercial market is the inability to load binary blob drivers without maintaining a custom kernel.