For their intended purpose Rivendell is perfect albeit pricey. The head tube and rim brakes work perfectly. I ride in the rain and have NEVER had a problem with cantilever brakes. Manufacturers played up disc brakes to sell more bikes. Rim brakes and 1” head tubes get the job done. You’re doing yourself a real disservice by not trying one out.
I do see good arguments for going with rim brakes for the intended use.
However, I see no practical benefit in threaded steerers and headsets, only downsides. I would tolerate it on an old vintage bike, but it is a dealbreaker for me in a new frame, especially onr I am paying a lot for.
Threadless is one of those few innovations that “new and improved” was also a lot simpler. The first time I worked with a threadless headset and steerer, all I could think was why the heck it was not done this way all along.