Simpler decision tree:

Choose Postgres by default. Choose MySQL only when you have a specific requirement that cannot be satisfied by Postgres. Choose document-oriented only when there is a specific requirement that cannot be satisfied with a jsonb column in Postgres. Choose column-oriented as a secondary data store that ETLs from the primary (preferably Postgres) when you have to run high volume analytics.

Nice! This is a much simpler decision tree. Google uses column-oriented as their primary database, but you're probably right that unless at massive scale, it only makes sense as a secondary data store (e.g. data warehouse)