The downside is literally exactly the same as the upside: you have to bootstrap from literally nothing for every single request. Well, it depends on how it's i

The downside is literally exactly the same as the upside: you have to bootstrap from literally nothing for every single request. Well, it depends on how it's implemented, and how pedantic someone gets about what "shared nothing" means. There is a long history of unix daemons that initialize, listen(), and then fork off a child process whenever a client connects. The child does all the work and the parent goes back to listening. You can do the "up front" work once and then each child can only modify their copy of the data, preventing it from interfering with the next request.