This FAQ is more for you to answer than for us. If you’re in a room with 50 people (or 100, or 10, or 500), do you really want to go from person to person through the whole crowd? Sometimes yes, of course you do, but much of the time you’re at an event for a particular purpose (or set of purposes).
You want to meet like-minded people, you want to meet people of particular skills, you want to meet people with certain affiliations. Other than asking everyone to carry around a sign, how do you filter out the random from the targeted? What is it worth to you to be able to talk to 10 people with whom you have a high chance of interest instead of 30 where you have no idea?