Until I left the dating scene for a partner last year, I wouldn't date men more than 5 years younger than me, with one disastrous exception at 10 years younger that only proved my rule. Here's why I have no hunger for younger men, and reject those who approach me:
There's a generational disconnect that neither of us is likely to bridge. Most of the things we know are grounded in the era in which we lived, especially during our formative years. Certainly cultural things likes movies, music, TV, styles in every field, catch phrases & slang, celebrities and so forth become part of our personal fabric. Added to that are politics, world & national events, educational approaches and many more.
That cultural snapshot we carry with us influences how we frame our references, view the world, and molds even the very manner of our thought processes. When those cultural references are seriously out of alignment, we have the infamous "generation gap" that my own generation made popular in the 1960s, and which can still exist today.
As a result, a date that's something more than a trick with drinks thrown in will not work for me, if I can't communicate and relate to the other guy. He's talking 1990s and I'm talking 1970s, and those can be like foreign languages to each other.
It's the classic idea of having something in common or not, and for me a fundamental of that commonality has always been shared experiences and outlook. I find it with my own age group, and a little older, but not much with the younger crowd.