Titan is a good existence proof that moons can retain dense atmospheres, but the exact reasons for it are complicated. Why don't any of Jupiter's large moons ha

Titan is a good existence proof that moons can retain dense atmospheres, but the exact reasons for it are complicated. Why don't any of Jupiter's large moons have dense atmospheres? Maybe radiation around Jupiter causes more atmosphere loss. Maybe it's just random. There's actually an argument that gas giant moons might be more capable of retaining atmospheres, all other things being equal, than equivalent free bodies, because gas molecules they lose will remain in orbit about the gas giant and eventually re-join the moon. So, moons with atmospheres are clearly possible, but it's very unclear how frequent they might be, or how their prospects compare to those of regular planets.