Alcohol is nothing bad but it is not healthy and it doesn't help to make true connections. People are more present and clear for communication and exchange when they are sober. Sad enough that most of us live in a society where alcohol is such a standard and many people don't enjoy as much when they go to a party without drinking alcohol.
What is so important about that or so addictive that people can't just drop it for after parties with more clarity and true presence?
I drink once a year and enjoy it but I have had my best parties without alcohol and communication is certainly better and more meaningful without it - let's say most of the time.

The people make the place and alcohol or not will make a huge difference.

This question may make sense to ask when deciding about alcohol or not: What is the intention for the party and where should the focus be?