There is still no equivalent to Microsoft Exchange, Group Policy, Enterprise PKI, and a bunch of other things in the Linux world. SAMBA copies Active Directory, but it's a direct clone, not a unique product.
Not to mention that SQL Server isn't somehow "copying" UNIX. Its performance and feature set blows most of the open-source databases out of the water, with only Postgres having superior features (but not performance).
Microsoft essentially invented OLAP with SQL Analysis Services, and they still have the most popular products in that space, such as Power BI.
Etc...
The tooling around SQL Server is decent
Which also means fewer attack vectors.
UNIX was not an option for most people which is one of the reasons why NT killed the Unix workstation market and Microsoft software like IIS, MS SQL and Exchange was already established when Linux gained mainstream adoption.