Why only being compatible to SQL:92 and not at least to SQL:2016?

Why only being compatible to SQL:92?
There’s SQL:2019 close to completion with graph structure support: https://modern-sql.com/standard .
And SQL:2016 already has nested structures (JSON): https://modern-sql.com/blog/2017-06/whats-new-in-sql-2016 .

Hi,

I didn’t see anything in the spec that’s specifically incompatible with SQL:2016.

Just my two cents, but I think the idea here is to extend SQL with additional functionality to support schemaless and hierarchical data, while making sure existing SQL constructs still return the same results as they do with vanilla SQL.
Any implementer of the spec can choose to be compliant to any version of SQL, but there’s really no need for a syntax extension to require anything more than the bare minimum.