Unfortunately many people rely on proprietary software packages that don't run on Linux, such as Microsoft Office, the Adobe Creative Suite, and other desktop software tools that serve various niches like CAD, music, video production, desktop publishing, etc. There are often FOSS alternatives that run on Linux, but sometimes these alternatives have shortcomings that hinder adoption, such as lacking necessary features, having imperfect file format compatibility with proprietary file formats, having a less intuitive UI, etc.
With that said, the desktop Linux ecosystem has come a long way over the past 20 years that I've been following it, and I think desktop Linux serves the needs of people who are not reliant on the Windows and Mac ecosystems.
Even if the alternatives were just as good or better, their workflow is likely entirely different. Different keystrokes, different ways of doing everything, slightly different quirks than the "brand name" software.
I like some of the Linux alternatives more than the "brand name" software, but I don't work in media or document creation. If I had all the keystrokes for Adobe Premiere memorized, it would be a pretty tough sell for me to drop that to move to something like Lightworks or something.
The thing is that they're just tools. Having some keystrokes memorized does not mean you can't learn new keystrokes or, in some cases, you can't change them.
When I worked at uni I saw people rescinding when applying for a web design job because the computer they gave to them didn't had Photoshop installed - not that it was required to do anything super special, they just needed to crop images and export them to a given size. People, specially in the media sector, are incredibly dependent on "brand name" software.
I don't disagree, people can learn new keystrokes and workflows, but it just makes it a tougher sell.
Imagine that you've been using Windows for twenty years. You have been doing paid professional work with Adobe Premiere for twenty years. You have a workflow with the two that has worked for about twenty years. Linux might be better, but it's probably not that much better than the setup you have right now, and the applications you have built your business on don't exist on that platform, and there would be a pretty steep learning curve to pick up the new stuff.
I can't speak for anyone else, but I probably wouldn't move to Linux at that point.
Now, if I were already using the Windows version of Lightworks or Resolve, that might be different; a lot of my knowledge would transfer over, and that might be enough for me to change over.
With that said, the desktop Linux ecosystem has come a long way over the past 20 years that I've been following it, and I think desktop Linux serves the needs of people who are not reliant on the Windows and Mac ecosystems.