The areas where OpenBSD can compete (in addition to the ones it already fights in, like routing and network-edge roles) are cloud deployments and orchestration. If it were as easy to run OpenBSD for development as it is a containerized Linux, people would pick the more secure choice. They could also make prebuilt appliances for the most sensitive components in a deployment (databases etc).
Now what exactly created this divide to begin with is a matter of debate but it took place mostly in the 90's and the very early 00's. By the mid 2000's it was clear that BSDs would have a really hard time ever catching up with Linux, especially for non-server applications.
Paradoxically it might be partially why BSDs are so clean and tidy: fewer features, fewer contributors and of course they're making a complete operating system instead of just a kernel or just a distribution.
FreeBSD remains my favourite OS for servers, it's rock solid and a joy to administrate. Unfortunately for the desktop I've given up almost a decade ago, driver support is just too lackluster, especially (as you mention) for proprietary software that can't be easily ported.
The Linux users gave back (often because they had to) and the BSD users often didn't.
So in the long run it is back to the old freeware days, with the lower lever free and everything on top closed, with zero contributions.
Sendmail, postfix and qmail all had BSD-ish licenses, and those three covered quite a majority of all opensource mail serving at the time of BSD-vs-Linux "in the same early years"
So, nah, it's not the license.
vmctl create disk1.img -s 10G
vmctl start vm1 -d disk1.img -b /bsd.rd -L -cGood! On FreeBSD, for now, sanity prevails!
This is one of many reasons not to use Electron. Claims of Electron portability are a sham.
* Electron apps - VSCode, Atom, Slack, almost every universal desktop app that gets released today. Individual ports of apps to FreeBSD exist, but there is no way to automatically build Electron apps for any of the BSDs.
* Good desktop virtualization - KVM, VirtualBox (okay FreeBSD has these in theory), VMware
* First-class Docker and desktop container support (FreeBSD jails exist but there is no container ecosystem like there is on Linux)
You can still run Firefox, mail clients, vim/emacs, Unix utilities and LibreOffice on any of the BSDs just fine. They're lacking other niceties however. And that's a bad thing in my opinion - although it's mostly not the fault of any of these projects. Some people think BSD is better for lacking those options, but I can't live without them for one.
It's unfortunate: Linux and the BSDs used to have more or less the same application support. Anything Unix-y ran on anything Unix-y. There was nothing stopping you from having an OpenBSD desktop almost identical in function as, say, a Xubuntu desktop - one that looked much cleaner on the inside. But once broader commercial interest started happening for Linux, the BSDs were mostly left by the wayside in application support.