It has many technical limitations that I'm aware of. Large TCB, less fault-tolerance, supports less COTS hardware than Linux, less automation software, less multicore, desktop as you mentioned, weaker in virtualization, no mandatory controls on apps, less integration with cutting-edge security tech (eg CheriBSD, SoftBound)... could be more but that's off top of head.

Harder to say whether it's easier to bring OpenBSD to where competition is on these or to bring competition's code to where OpenBSD is, esp as some safety/security tech makes that less relevant. Hard to say...

Regardless, it's a high-quality UNIX that's worth having around. I'm glad to see them improving in areas where it's weaker while not throwing away strengths like some projects would.