This points to the most obvious technical obstacle to implementing @icaria36’s idea. If a server pushes data at another server, that’s a juicy target for automated spam. Services prevent that by making anyone who wants to push data to their server get a unique API key, which can be revoked if they abuse it (or the service operators just don’t like what they do with it).
Any website that could be used for one-click publishing would need an API key for each music platform it wanted to publish to. So someone could design a web app for this and publish the code for anyone to use. But each person who set up an instance would have to get their own API key for each platform they want to publish to.
If you did it as a local app, as @unspeaker points out, you’d need to support a lot of OS. Also, while you wouldn’t need a server-to-server API key, big platforms often require a client-to-server API key. So in that case each artists publishing releases would need to get multiple API keys and keep them live.
The thing is, there’s no incentive for the corporate platforms to cooperate in any way with anything like this. On the contrary, they have a strong incentive to prevent this kind of thing, which could turn music hosting back into a competitive market.
The most futureproof solution would be to get both musicians and audiences off corporate platforms and into an ActivityPub-driven music discovery and purchase network. But the obstacle there is a classic collective action problem.
Unfortunately, there are no easy solutions to breaking the power of monopolies and cartels once they’re established. But maybe showing US and EU legislators that WIPO treaty rules against adversarial interoperation are working against the interests of most copyright holders could move the needle?