On the neo-chartalist theory, it’s a roundabout way of coercing labour. The State could say: ‘Do this work for me, or I’ll put you in jail.’ But it’s sneakier to say: ‘Do this work for me, and I’ll pay you this token, and if you don’t pay me the token later, I’ll put you in jail’.
I think discussion of final causes is anathema to the positivistic, naturalistic image that macroeconomists want to maintain of their science. Most natural sciences have long accepted that discussion of different types of causation (besides efficient causation) is perfectly appropriate at times. But during the 60s and 70s, when macro was defining itself as a rigorous science akin to physics, it was a defining mark of proper science to only ever discuss efficient causation. I guess insofar as political economists defer to macroeconomists, they retain this prejudice.