well .. I guess that would work ..
Seems to me seeing other people suggest using that link. And many of the other form comments.
The thing is weird that I can't get it to work.
This is not using mDNS (Bonjour) for name resolution. This is simply your Asus router intercepting the http request and then displaying your router’s web config page.
It's not that you need a DNS setup for it to work, more that if you had set one up it may interfere with being able to access the hub in this way. Like you I believe it should work without any additional setup required.
I'm a non-Windows household. I've got Apple and Linux and while I had never had reason to try "hubitat.local" before this Topic, it does work for me using the name(s) I set in Hub Details. I'm not surprised and imagine that reflects exactly what you mention: