I think you misunderstood. Of course there's always a stack trace; you're still executing code. But with message buses and magic reactivity systems your stack trace always just goes to `mainEventLoop()` or `processEvents()` or whatever.

It doesn't go to the thing that actually caused the change as it would if you used direct function calls. I'm not saying it's a deal breaker, it's just a notable downside of those architectures.