I suppose the dilemma of universal machines is that they can be used for consumption as well as production.

Treating apps as fields in which consumers can happily graze, and sticking up electric fences all around, is probably a good enough way of separating the sheep from the wolves.

I wonder, however, if the application is really the relevant level of scale when machines are used for production ? A work-flow of any real complexity will need a tool-chain - hence the venerable unix pipeline.

Electric fences ? Well, it's one way to manage sheep (or prison populations) but on your own farm, you need to able to switch them off.