…limitations in watchOS 4 make it impossible to deliver standalone podcast playback with the basic functionality and quality that people expect.
Marco Arment, creator of the popular Overcast podcast iOS app, extensively details WatchKit’s limitations and how it can’t realistically be manipulated to produce the app we all so desperately want.
Reasons vary from file transfer nerfing, lack of streaming audio functionality but are nailed shut for Marco with the Watch’s inability to play audio in the background. As a result, syncing, a primary function when listening to podcasts across multiple devices, can not be achieved.
It’s an interesting, albeit sad read.
Source: What we need from Apple to make standalone Apple Watch podcast apps – Marco.org