I think you may have cause and effect backwards here. Needing to move to less popular and populous places to form a household likely discourages young people from forming households.
For many the only way they can afford to form a new household is by committing to moving away. That puts a huge barrier in place. The fact that “away” means “less popular / populous places” doesn’t help at all.
You’re probably looking to move into your top earning years so it’s not a great time to move to a smaller market.
If you’re getting married, you’re probably around the age to be having children. Raising kids, in my experience, gets progressively more difficult the less urban you go. You’re also moving further away from your support network—who’s going to watch the sick kid if you can’t miss work? Grandma who’s a 2-24 hour drive away?
If the only way you can afford to start a new household or a family is by cranking life onto hard mode, why would you?