Rails doesn't have fast boot times even now. exiting after each request would result in much slower apps. Also, you couldn't reuse database connections so you'd

Rails doesn't have fast boot times even now. exiting after each request would result in much slower apps. Also, you couldn't reuse database connections so you'd get additional latency built into starting up a new connection with your db. This isn't just a Rails thing either. FAAS is a good thing. I'm a big fan. It's essentially the same thing as CGI which was awesome back in the day, BUT there are multiple good reasons to choose a framework that isn't constantly exiting.