It sounds like you're basing this argument on hearsay and not personal experience (shocker.) I have various audio setups with different macs and interfaces and no OS update has broken anything with my setups since 10.6 era.
https://www.izotope.com/en/community/blog/product-news/2016/...
Personally I had to spend a few hundred dollars upgrading my audio software that worked in Mountain Lion so it would run on El Capitan. I'm still running into a few glitches in places.
I've been running software on Sierra that is only certified by the developer for Snow Leopard through Yosemite, and it still runs just fine for my needs. Apple puts a lot of effort into binary compatibility.