“Agents - Complex Crowd Simulation” is one of the few addons in the “Crowd Simulation” category that does some actual simulating using more complex calculations akin to game AI logic.
Most other addons such as Procedural Crowds or Horde populate your scene with characters based on simple rules. That is not necessarily a bad thing since most projects do not require complex character interaction. Just having a lot of people that seem to be walking around, idling or cheering is enough and the above-mentioned addons accomplish that quickly, easily and with good viewport performance.
However, if you need a more complex behavior model for your crowds, “Agents” may be what you’re looking for.