I also enjoy the polish Apple provides in other ways -- the platform features you get if you're on a Mac, use an iPhone, have a Watch, etc, are all pretty great. Cobbling together something like that on my own under Linux probably isn't possible.
If you don't need that kind of thing then Linux is indeed pretty good these days. But especially in a business context, a lot of people do.
Why do I have to use Onenote? It's free. It syncs well with other computers and mobile apps. Sharing notebooks with other people works and is free. It's intuitive enough that my wife can use it. The search works, the formatting is rich enough, you can paste in pictures.
I don't need the rest of Office. The online versions or Google docs are good enough. If I can get Onenote and Fusion360 working well on Linux, I would likely switch to Linux.