And yet many the web or iPhone dev will wildly smear ad hoc state machines within modules and across modules in their codebase via if/case, maybe dressing it up

And yet many the web or iPhone dev will wildly smear ad hoc state machines within modules and across modules in their codebase via if/case, maybe dressing it up a bit with redux, et al. As the codebase grows, teams of those devs will labor under the constant threat of suffocation from the thrashing-swirling spaghetti of events and side-effects they themselves authored and don't know how to tame.