This hasn't been my experience. I have been running a custom built Mac for the last 5 years and my interfaces have always worked after the update. I think the main thing is making sure that whatever device you use has a driver that has been updated for the newer build of Mac OS. This is really only been a problem the last couple of versions. I use a Line 6 interface and they have been pretty good about updates. If your device manufacturer is less than stellar on updates there can be third party drivers that will make it work although for some this is obviously not idea.
I don't want to start a Mac vs PC war, but both platforms have their strength and weakness. But in my experience, the OS update issue on a Mac has been maybe the biggest weakness for DAW users.
I downgraded my i7 Mac Mini server to Mavericks because of all the issues. At some point I won't have a choice and will have to update to whatever is the latest OS. That will be a long day of updating. IMO troubleshooting Windows is a lot easier and intuitive (in a relative way) than a Mac now.
I'm no Windows fanboy, but at least they usually take backward compatibility in to consideration when they come out with a update. Apple just says "it's not our problem".