It sounds innocuous, but we were planning on supporting a lot more databases, and when you start needing to build drivers for MySQL, Postgres, SQL Server, Oracl

It sounds innocuous, but we were planning on supporting a lot more databases, and when you start needing to build drivers for MySQL, Postgres, SQL Server, Oracle, Redshift, etc etc anything that makes this step more brittle starts to add up. There are a lot of things that are mostly painless if you're deploying and supporting a single instance that become nightmares at the scale hundreds or thousands of installations you don't control.