I have no idea about the OP's system, but I can see some advantages to breaking components up across a network, at least for vertical scaling. First is that server prices do not scale linearly: four 10-core machines will generally be cheaper than a single 40-core machine. Second is that some programs can hog memory/CPU time; forcing programs to run on their own machine can ease some of that contention. These gains can seem rather small, but can make a big difference at large scales. If you don't mind the drop in latency it's a perfectly acceptable architecture.