Author here - it's just to reduce support surface area. I know I'll need PostgreSQL's full text indexing and GIN indexes for hashtags/search eventually, and I probably also want to use some of the upsert and other specialised queries, and it's easier to just target one DB I know is very capable.
For reference, when I say "small to medium", in my head that means "up to about 1,000 people right now".
For reference, when I say "small to medium", in my head that means "up to about 1,000 people right now".