What’s the appeal of Microsoft SQL Server 2019 over something free like PostgreSQL or MariaDB?

Microsoft Support, T-SQL is quite the good dialect and muh windows ecosystem.

📌

Windows vs Non Windows servers.

You wouldn't use mssql on a linux server would you?

The whole package - Visual Studio integration is beyond most SQL tools, better integration with other MS products, it has direct Azure integration (deploy from VS, create migration scripts, have roles, access policy, cloud init / update as a part of your project on git, ...), data warehouse (big data analytics support the same query language), co-working tools (live share)...

@kescherRant I can also jump from 30,000 feet without a parachute 👀

Somethings are just better off not doing.