While battling Dragon Ball’s villainous Granolah, fans are given the full picture behind the bounty hunter’s motivations in attacking Goku and Vegeta. The Namekian that raised Granolah after the death of his mother and basically the rest of his planet tells him the story of Planet Cereal’s destruction and his subsequent survival. Granolah learns that Goku’s father, Bardock, was the reason he survived the onslaught, and while that should squash the issue between the vengeful bounty hunter and the two Z-Fighters in the present day, there were plenty of other Saiyans that day that weren't even remotely as heroic. In fact, the Saiyans responsible for the destruction of Planet Cereal were seemingly invincible, with the Cerealians’ last shot at defeating them coming up short.
In Dragon Ball Super Chapter 77 by Akira Toriyama and Toyotarou, fans are given for the first time the complete origin story of the seemingly villainous Granolah. The manga opens forty years in the past, on the day the Saiyans invaded Planet Cereal, wiping out almost the entire nearly instantaneously. The Saiyans were able to complete this feat so quickly by aligning their invasion with a full moon, offering them the ability to transform into Great Apes and unleash their destructive power upon the planet. The Cerealians quickly realized that the source of their Great Ape power came from the moon, so they destroyed it, hoping to rid the Saiyans of their power in the process. Unfortunately, that didn’t happen.
After the Cerealians destroyed their moon to cut off the Saiyans’ Great Ape ability, they were successful in doing just that, cutting off their power to transform into Great Apes. Unfortunately, however, the Saiyans were more than powerful enough without the transformation to conquer the planet, especially after the damage they already inflicted while in their Great Ape forms. While destroying the moon was a valiant and clever maneuver by the Cerealians, their efforts were hopeless and were far from enough to stop the Saiyan army. Plus, if the Saiyans were so inclined, they could have transformed into Great Apes even without the moon, making its destruction even more tragically pointless.
In Dragon Ball Z after Vegeta lands on Earth while under the employ of Frieza and challenges Goku, Vegeta learns quickly that he needs an extra boost of power to finish off Kakarot once and for all. Vegeta is initially angry as he meant to have his arrival on Earth coincide with a full moon just in case the Great Ape transformation would be necessary. However, Vegeta uses an alternate method in unlocking the destructive transformation by simulating the light of a full moon with a Power Ball, a Saiyan-made power source that they can use to become Great Apes without a full moon.
After Vegeta’s show of power in the early pages of Dragon Ball Z, fans know that even without a full moon Saiyans can still become Great Apes. Plus, even if the Great Ape transformation is off the table completely, the power level of most Saiyan warriors is far superior to most of the life forms they conquered under Frieza. Dragon Ball Super just proved that even destroying the moon isn’t enough to stop Saiyans while they’re in their Great Ape forms, both because of their general power levels and the fact that alternative methods can be used to reach their horrifying transformation.