It's a yoke I'd be pretty happy to accept as an application developer. No, it's not necessary to couple the two concepts. But nine tenths of good language design is coming up with good abstractions, and good abstractions always involve some conflation. And from a software engineering perspective I can see some good reasons for this choice.

One is that it creates some predictability around how errors will be handled. As a producer of components, I know that within this component I have to accept that certain classes of error will always cause a fast failure, and other classes of error should be handled as immediately and gracefully as possible. Compared to the mishmash of different error handling philosophies that I currently encounter when working on different components, this seems like it might be a welcome improvement even if it isn't a complete solution.

As a consumer of components, I think it's even better because it enforces still stronger predictability. I get a couple nice guarantees out of this. One is that critical failures bringing the whole component down means I encounter fewer situations where I'm unsure whether the overall application is in a consistent state, because 3rd-party component developers have fewer opportunities to do weird things with exceptions. The other is that I can always defend against critical failures in 3rd-party components bringing down the whole application. That isn't always easy to do in vanilla C#, where FailFast exceptions always bring down the house and the best defense against that is to resort to the hassle of process-level isolation. For systems programming I imagine such measures are even more irritating, since process-level isolation creates performance overhead.