Many of the Big Business use a form of Linux as a Backend with Windows facing the customer end of the business. It gives them greater scalability and reliability but retains the Commonly known OS for end users.
Small Business however are unlikely to run any form of Linux particularly if they want or need to share files with customers as the Native Linux Documents just are not readable in a Windows Environment.
Then you have Specialist places who run some very specialized software which dictates what OS they need to run on so if you are doing Video Editing Special Effects the Software of Choice runs on Linux so that is what you need to use if you want your output to look professional. Water flows/movement in Video are particularly hard to get right and currently I’m only aware of 1 piece of software that currently comes close so that is what is used most often when you are doing that type of work.
Similarly Graphic Artists tend to rely on Apple Products much more than Microsoft Products so their System of Choice is the Apple Version of BSD Free.
Linux is becoming more popular for businesses because Linux is a free and open-source operating system and its source code can be used, modified and distributed by anyone, even for commercial purposes.
Linux is an open-source operating system that every business really need. Windows may need frequent hardware upgrades but Linux gives any business outstanding performance and scalability.