As you may be aware, the SQL Server on Windows Containers Beta program began in 2017. It has remained in Beta mode meant for only test and development environment until now. Due to the existing ecosystem challenges and usage patterns we have decided to suspend the SQL Server on Windows Containers beta program for foreseeable future. Should the circumstances change, we will revisit the decision at appropriate time and make relevant announcement.
I never heard of many people using Widows containers, but with the differences in available products and features between Windows and Linux versions of SQL Server, I can see why some people would want to use them.