[IshKebab]

> There’s always a stack trace.

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.

[TeMPOraL]

As GP said, you have to compensate with some form of logging/tracing. At the very least, if you assign an ID to every event, then to debug an issue you can start logging sends and receives, and work out the relationship.

[IshKebab]

Yes you can do that but it's still worse than a proper stack trace that goes back to where the message is generated.