Declartive programming declares what the state of the database should be. It does not care about the current state. It simply focuses on getting the database to the declared state.
Terraform is a declarative DCM tool.
Imperative programming requires the author to be aware of how the database is currently configured. The author must write the code that gets the database from the current state to the new state.
Schemachange is an imperative DCM tool.
Schemachange was selected over other DCM tools because there is no additional learning curve. You write SQL. Also there is no extra infrastructure needed to manage the state. No extra cloud service. No provisioning a separate database for tracking the state.
Snowflake is rolling out native declartative functionality with their create or alter statements. This is limited to Tables and Views at the end of 2023, but is something to monitor.