I don't like it - you're forced to pass around this token, constantly manage the lifecycle of cancellation sources - and incredibly bug prone thing in async context, and it quickly gets very confusing when you have multiple tokens/sources.

I understand why they did it - a promise essentially is just some code, and a callback that will be triggered by someone at some point in time - you obviously get no quality of service promises on what happens if you cancel a promise, unless you as a dev take care to offer some.

It's also obvious that some operations are not necessarily designed to be cancellable - imagine a 'delete user' request - you cancelled it, now do you still have a user? Maybe, maybe you have some cruft lying around.

But still, other than the obvious wrong solution - C# had a Thread.Abort() similar to the stop() function that you mentioned, that was basically excommunicated from .NET more then a decade ago, I'm still not happy with the right one.