In Chapter 13 of "We Are Anonymous" Parmy Olson writes this: "Chanology and Operation Payback had shown that if they were manipulated in the right way, Anons in their hundreds would suddenly want to collaborate on a raid or project. But the key to that was making the raid fun and exciting." (p. 195)
This has been a constant key to Anonymous operations, not only to persuade masses of people into participating in an operation or "raid" but to make them feel like they're actually part of something big, even if the role they're playing is less than significant. This is an odd trait within the collective considering that the most successful Anonymous operations in history have been carried by small handfuls of people (like in the case of LulzSec). Yet, recruitment drives are constant for a very specific reason.
A good example of this are DDOS attacks, which Olson describes as being waged by two types of soldiers: those using the Low Orbit Ion Cannon (LOIC) and those commanding vast legions of zombie computers called botnets. (p. 74) As Olson points out in that same section, botnets are vastly more powerful than LOIC, which is comparatively a popgun that requires thousands upon thousands of users all firing it at once to inflict notable damage. Olson also points out that as Anonymous matured and grew, the need for LOIC became less and less necessary to actually bring websites down. (p. 74)
Yet, well into 2011, Anons were still being asked and persuaded through ominous "Message to Scientology"-styled videos to participate in big DDOS attacks, even though the operations were primarily being carried out by a handful of large botnet commanders.
The reason for this was simple: botnets are very difficult to track and bring down. LOIC however, despite what the software claims, does not protect those who use it from having their IPs tracked. Many additional steps are required for those firing that cannon to keep their location safe. But many users didn't realize that, nor were they made explicitly aware of this.
Therefore the need for mass participation was simple: let the "newfags" fire LOIC at the target while the botnets are hitting the website. The website goes down and the other Anons in the attack think they've done something great and are willing to help with further operations. The illusion of participation and success excited many to join the cause against the enemies of WikiLeaks and later the entirety of the cybersecurity industry.
The Paypal attack described by Olson (p. 110) was largely carried out by botnets. Yet, those who were arrested months later -- many of them 16-year-olds in highschool who had their houses raided by SWAT teams -- were using LOIC to attack financial institutions, while those controlling botnets remained at large and unknown until much later. The main perpetrators, those running LulzSec, were found and tracked much later than they would have been had the FBI not been running around chasing false or insignificant leads tracking those using LOIC.
The individualist and anonymous nature of the collective lends itself to the weakest being picked off and sacrificed to the feds without barely a care. And that's the danger of getting involved with Anonymous without entering with eyes wide open: they will manipulate you into participating and then let you take the fall.