Thomas Reid, in "Essays on the Intellectual Powers of Man" in 1785, wrote that, "In every chain of reasoning, the evidence of the last conclusion can be no greater than that of the weakest link of the chain, whatever may be the strength of the rest," which has been condensed into the more familiar and modern phrase, "A chain is only as strong as its weakest link."
This short excerpt identifies the real danger that lies in groupthink, mob mentality and any philosophy that ordains the group as being more important than the individual. Because a group, as being synonymous with a chain, is only as strong as its weakest member.
Because groupthink does its best to eradicate any semblance of individualism, this concept is essentially lost on them. In their view, the group can only be strong, because there is power in numbers. And that is all they see the individual as--a number. They cannot be as weak as their weakest member, because the weakest member (i.e. the individual) doesn't exist. Only the group exists.
This presents an exceptionally dangerous worldview. By erasing the individual, the individual loses any passion, drive, wherewithal, strength or motivation to do anything for themselves, because they truly believe that they cannot accomplish anything outside of the group. Which is obviously a direct result of the fact that groupthink tells individuals that they can only find those things, and above all else, their identity, from the group itself.
The New Oxford American Dictionary defines "identity" as, "The fact of being who or what a person or thing is." So when a group tells an individual that they can only find their identity in the group, it changes the meaning of identity from being, "Who I am" to, "Who we are." Which, is honestly counter-intuitive when considering that what they are essentially saying is that who someone is, as an individual, can only be defined by the group that they are part of.
There is an inherent pride associated with individualism. A pride that only comes when an individual puts in the work, blood, sweat and tears into accomplishing something. A pride that no one can ever take away from the individual, because it was the individual alone that was able to bring it to fruition. That feeling is something that no one should ever be unable to experience.
It's true that a chain is only as strong as its weakest link. But following that same logic, the weakest link is only as strong as it allows itself to be. Which is why I am adamantly opposed to groupthink and the breakdown of the individual; because if we can only find our worth and our identity through a group, rather than being an individual, then we will never be capable of strengthening our link.
Don't misunderstand me here: human beings are social creatures. Our evolution has progressed at the rate that it has, and has resulted in human beings becoming the apex of speciation, in part because of our complex social systems. However, social systems evolved because of the individual, not in spite of it.
Remember, the phrase goes, "What's good for the goose is good for the gander," not, "What's good for the gander is good for the gander."