People are also immediately using the deploy interaction in Buster Quests when the instance hits 8 people, ignoring people who have yet to join a party. It's annoying. Some people also hit the interaction at 7 people, ignoring the fact that if someone doesn't come, no one ever will come when the timer starts. Since matching will not work with quests already in progress.
In addition, party beacons are force removed when the quest timer countdown starts, which is completely dumb.
Not sure if story and public can do the exact same runs and play together. But last run I did for story, when someone dropped a party beacon, I tried to access it and couldn't join because people doing story can't join parties.
Active Recruiting is the option that puts you in the list of parties. Party Beacon is purely an in-instance/in-quest system. You can also fuse parties together by interacting with a party beacon as the leader of a party. (Only if the destination party has enough space.)