It's dps like this that lead me to say:
Presumably the reason you want to visit your friend after 8 is because you’re busy earlier (working, school, family etc.) If you can’t go later, you’ll either A) go earlier (instead of doing something else) or B) not go (because you or he are busy earlier). You’ll prioritize more important in-person activities and leave the less important activities to online interaction.
Do you see how in a large group a curfew can have a significant impact on spread, by greatly decreasing in-person interactions between people?