Just because people doing it doesn't mean its the best thing to do. Also how can I be wrong, you can disagree with me. Obviously I am stating my opinion on this matter. But so far I haven't seen any real arguments from your side contradicting what I said.
The best argument is that me and lots of other people use it successfully as a daily driver without any problems, because we obviously don't lack certain skills you may do.
Your argument is totally random`and makes no sense, you could also claim that Linux is only for servers because its mostly being run on those compared to its Desktop usage and Windows or MacOS on Desktop systems, but you don't, right?
Linus Torvalds himself doesn't like Desktop Linux, although he uses Fedora, but that doesn't make it any less justified as a Desktop OS, no?
OpenBSD comes with the possibility to run Xorg and you can install programs with GUIs like Webbrowsers, LibreOffice Suite, etc. And the performance constraints due to it being hardened can be untightened if you want or need to. You're literally making things up here.
You first sentence actually supports my previous statement, that OpenBSD is aimed at developers. :)
Why would I "untighten" the hardening and not just use an OS which is more suited to my needs? Even for privacy, which is much more relevant for normal usage, there are better alternatives to OpenBSD.