The next time you go to an event look a little more carefully. I speak generally. Men stand in open formats; women when they are talking to other women nearly always and men often, will be facing them.
This means they give their full attention to the person they’re talking to unlike men who spend lots of time looking around for the next opportunities.
For women what they are doing is admirable but it can often reduce the opportunities of others approaching as they will think you are in the midst of a private conversation.