The title and framing of this talk are weird and it's bugging me

The question could be paraphrased as "why would we need to efficiently store and retrieve data in a deterministic way when we have GenAI?" This is like asking "why do we need cars when we have speedboats?" or "Why do we need butter knives now that we've invented the chainsaw?".

The actual subject matter is "PostgreSQL with a couple of plugins can do pretty good nearest neighbour search". I've long been a big fan of Postgres. You probably don't need separate vector database engines, you can just use postgres for everything.