We tend to design API calls over the net as stateless. It's more efficient to implement in a server and prevents abuse (keeping client states on servers for unknown amount of time lead to DoS attacks).
A flow based system would require more flow on the other (server) side. Imagine each sentence to be a request in the following, and how many avenues of potential service abuse it could bring. That's why we avoid designs like this today.
Here lets's begin a new (cloud?) server definition. Inside this server definition let's begin network specification. Inside this network specification let's begin open ports specification. Here, there's a batch of ports we computed we need. Here, there's another batch of ports we need. End network specification. [...] Let's get back to that port spec, because of something emergent. [...]
