Why would we think other star systems would not have moons? They’re quite common to the planets in our solar system. The physics works the same way in other star systems.
My thought exactly. There are other fish to fry.
Actually 25% of the planets (Mercury and Venus) in our solar system don't have moons. If one considers only the rocky planets (which are the ones that might sustain life as we know it), then only 50% of such rocky planets have one or more moons.
Furthermore, only a relatively large moon is likely to make an effective contribution (in addition to the sun's contribution) to ocean tides. Also a large moon can help stabilize a planet's rotational wobble. Unlike the Earth's moon, Mars' moons are likely captured asteroids.
Since the GJ 9827d planet is only 0.0559 AU from its star (Mercury is 0.4 AU from the sun; Earth is 1 AU from the sun), its "year" is only 6.2 earth-days long. No wonder it has a temperature claimed to be 800 deg F.
It is far-fetched to use any claimed characteristics of such a planet in such close orbit around a K-type orange-dwarf star to hype for the existence of an Earth-sized, liquid-water-containing planet with a comparable moon at suitable distance from a G-type star (like our sun). But it can be used in more research grant applications.