i'll take a 100ms turbopuffer vector search plus a 50ms postgres-select-where-id-in over a 500ms all-in-one pgvector + join query.

When you only need to hydrate like 30 search result item IDs from Postgres or memcached i don't see the join being "too expensive" to do in memory.

For a large class of applications, the database join is the last step of a very involved pipeline that demands a lot more performance than PGVector can deliver. There are also a large class of applications that don't even interface with the database directly, except to emit logging/traceability artifacts.