IPC (networks, FIFO, pipes or whatever) decoupled services solve problems more on the ops side, from binary compatibility to resource segregation. They do very little on the dev side.
My point is that it's not a technology problem in the first place. It's a problem of clashing senses of style and taste. It's a culture problem. If you need to dress up your culture problem fix with a technology explanation, http is the way to go because it's widely understood and so boring that nobody is going to ask you to explain it in too great of detail.
Your language's module system is boring. An specialized web server is about as close to the opposite as a corporate structure will allow.
I agree it's suboptimal for performance. But it absolutely cannot be beat for business stability and flexibility. And your IPC costs generally do not dominate your request times anyway.
> That dumpster fire over there is not my problem
Without having to say:
I want to rewrite the whole thing from scratch