>>14258137It's mostly because the mass distribution of stellar objects is very concentrated in a comparatively narrow range, such that a star with a mass sufficiently high to form the stable center to a set of concentrically orbiting smaller companions stars is very rare from the outset, and has a very short lifespan as well. Between the mass sufficiently high for ignition, and the mass sufficiently low for longevity in the billion-year range, which represents more than 95% of stars, the difference is only about 1 to 20. By contrast, even Jupiter is only 1/1000th the sun's mass, and this is still sufficient to put its orbital barycenter above the photosphere. The smaller such ratios get, the less stable such arrangements get.
