i watched Alex Cole from Asana=>Convex on InfoQ talk about how everyone can be a fs eng (with Convex) & his explanation of the backend engineering it manages (load balanced vps cluster of backend api functions serving cached db calls to a frontend that is wired up with pubsub)...
and i thought yes this is a managed service and it ticks all the boxes. how it relates to your commentary is: i feel that composable backends and middleware with turnkey solutions (could be broken up into feature verticals, perhaps or industry verticals that specialize on a subset of features to serve a particular interest segment) is really where it's at imho. Classically, I would categorize this as systems integration or SI, as it is referred to in gov contract speak...
composable backends integrated for a purpose like the fullstack metaframeworks do by routing requests to various backend services (with Vercel its Lambdas, with something like remix-run it can hook into a bunch of runtimes like plain Express or something else Vercel Netlify Cloudflare etc) is a very solid target i think. and what Alex is doing over there with the Convex folks (basically leveraging the Asana backend model & making it a managed service) i think could be replicated to any kind or combo of backends.
All that to say, I can't relate to anyone who wouldn't want to use node.js as their backend runtime. j/k i get it.