They need multiple engines for landing. An empty Falcon 9 is already too light to hover or descend on a single Merlin engine at minimum throttle.

Both Starship and SuperHeavy can hover and descend with multiple Raptor engines firing. This gives them engine out capability while landing and a much safer landing profile. There's no need to perform a suicide burn where you only have a brief moment to get it right or you are crashing.