I'm a systems administrator for a small MSP. I've used Linux as my primary OS for 9 years, despise using Windows, and I can tell you with 100% confidence that nothing but Windows is ready for prime time, and for one major reason: _ease of administration_.
Think of the growth cycle of the vast majority of businesses. Almost all businesses are started and run by non-IT people. They buy Windows machines because they're simple(don't have to worry about OS installation, chosing a distro, etc), have Microsoft Office, and work with any and all enterprise software they use. This gives them a key advantage for small businesses. Like it or not, Linux is just relatively hard.
Where Windows _really_ shines, though, is when a small business transitions to being a big-small or medium-sized business. If you have a couple dozen computers and a couple dozen users to manage, do you think it would be worth it to have a linux admin spin up an LDAP server with kerberos and all the bells and whistles needed, then be hired to manage that infrastructure? No, they're going to contract someone to spin up a windows server to manage user logins, create a network share, and call it a day. The infrastructure is super-stable, and when the cost of labor is considered, it is considerably cheaper than letting the system be the plaything of a local Linux zealot.
It's only when you consider big and massive businesses that Linux can really be viable, and even then it ain't cheap. Most big businesses grew in a Windows environment, and switching the core of your IT infrastructure sure as hell better be worth it to warrant the massive labor costs, IT fire fighting, and drop in employee productivity that will result.
No, Linux infrastructure and desktops really only make sense for companies that are either highly technical, need absolute control of their hardware, are _extremely_ price sensitive, are (or hope to become) massive, or a combination of these.