A small point but I wonder if it’s worth considering governance arrangements over time as well as at a point in time. For instance, a ‘well-functioning’ democratic government over time may be a step closer to your idea of proportional decision-making in that power switches back and forth according, so a given coalition may have disproportionate power at any given time but something more like proportionate power over time (albeit very imperfectly and in complex ways).
A small point but I wonder if it’s worth considering governance arrangements over time as well as at a point in time. For instance, a ‘well-functioning’ democratic government over time may be a step closer to your idea of proportional decision-making in that power switches back and forth according, so a given coalition may have disproportionate power at any given time but something more like proportionate power over time (albeit very imperfectly and in complex ways).