Yes, girls date guys that are younger than them, it is not a new thing . For these girls, it is not a matter of how old a guy is but how well he behaves.
Contrary to what we see in our world today, many girls would date guys that are younger than them if he behaves matured. If a girl like certain habits or traits in a guy, even if she is older, she's likely to give it a shot and date him.
I think it depends on the actual guy and if he is mature and able to handle the responsibility of a relationship. The stage in the person's life should matter more than his actual age. The main drawback is the fact that when two people are closer in age, they tend to have more in common. It could be everything from life perspective to what type of music they like.
If the person is younger, they might not have the same priorities, and they may still be involved in partying, and more interested in doing that than having a committed relationship. However, a strong sense of adventure could be an asset to a woman who wants to be daring and try new things sometimes younger guys are better able to provide adventure and excitement in an older woman's life.