>>214654321
This
The whole reason Freiza destroyed Namek was because the troops were noticing that even the low-class saiyan warriors were showing increases in power levels as they fought more
He only spared Vegeta because he was no threat when it was only him, Nappa, and Raditz, and also because his power level barely moved since it was already high enough that he wasn't putting in any effort for any of the missions (also because Freiza liked turning literal royalty into his slave)
If the entire Saiyan race managed to get as strong as Vegeta though, that could actually pose a threat if they all became GIANT MONKEYS