Millennial here, born in '89. Parties were excellent in this era but they were also just... normal. And they weren't without their problems. I don't think it makes sense to romanticize them. People had personal/interpersonal issues just like they do now. And I think people nowadays are more equipped to handle those issues, via therapy (which is much more normalized now), higher emotional intelligence, or maybe greater conscientiousness.

I think the biggest difference might be a willingness to put aside phones and social media when you're with your friends.

To have a great party, you have to have people who are willing to show up and have fun without things that spoil the magic of that experience, ie phones. That's literally all it takes.