Scratching my head a little bit here, I'm not sure how this differs from NextJS (or Vite) with a layer of drizzle & better-auth.

Not that that layer isn't important. We ended up building something like this at Ingram, nextkit: https://github.com/ingram-technologies/nextkit - but we distribute it as a set of micro libraries that work well together rather than a unified framework. (Auth is nk-auth, built on top of betterauth, and sql is nk-db, built on top of drizzle)

You got to pretty much the same conclusions we did though regarding the "why".