As a whole? Basically none. It’s advantageous for the males though, it’s something that evolved in a context of sexual conflicts (males and females have contradictory evolutionary optima). Here the males advantage is to have a many mates as possible while the female is advantaged by being choosy regarding its mate(s).

Evolution is not always about optimising things for a whole species.

When you’re a shitty little insect it’s easier to knock her up if you merely have to aim for “in her body.”