There are larger issues here about using HTTP for frequent, small, messages. Arguably, HTTP isn't an appropriate protocol in these circumstances, or other workarounds such as long polling or pipelined requests would work better.
The protocol overhead associated with making small messages is being addressed in HTTP/2. Thus, the limitation isn't inherent to HTTP, it's merely a consequence of the choices in one specific manifestation of HTTP: i.e., HTTP/1.1 and earlier.
The major reason is already implicit here: authentication isn't easy to coordinate.
The protocol overhead associated with making small messages is being addressed in HTTP/2. Thus, the limitation isn't inherent to HTTP, it's merely a consequence of the choices in one specific manifestation of HTTP: i.e., HTTP/1.1 and earlier.
The major reason is already implicit here: authentication isn't easy to coordinate.