From where do you get that sql server does not support columnar? That is a wrong claim.

I don’t think the OP said that SQL Server doesn’t support columnar, only that by analogy SQL Server is primarily a row store (which for most of its history was true).

Columnar technology in SQL Server only became usable in SQL 2016 (it existed in 2012 but was too restrictive — I know because I tried to use it).

In 2016 and above, you can either create a columnar index (non clustered column store) or convert an entire table into a columnar table (clustered column store). The technology is actually pretty impressive and I’ve used it in production where I have row stores coexisting with column stores within the same database.

Quite interesting read about how timescaledb turns a row store (psql) into a column store.