obviously I'm not trying to defend creepy groomers chasing after kids and I also don't agree that there's any real biological imperative for grown men to be chasing after barely-legal teenage girls either, but there is definitely more of an evolutionary benefit for women to go for younger men.
as men get older, their
sperm degrades - the wall, so to speak, is hit full-speed at around 35-40. after this, it's more likely for the pregnancy to end in a miscarriage and for the child of the pregnancy to have developmental disabilities and other disorders. to summarise, your sperm turns retarded the day you hit 35 and your kid is gonna end up having mega-autism.