Group mentality has a negative connotation these days, like mob mentality.  But it has a positive side as well.   In business, it's called collaboration.  People working together for the good of all in the group.   
    Have you ever seen a flock of hundreds of birds turn on a dime?  They could never do that if they insisted on being complete individuals rather than part of a group.  
    Being part of a group has advantages.   But in order for a group to function, it must have rules.  Rules for who can be members of the group and rules of behavior for those who are members.  Whether the group is a nation, a club, a church, or even a gang, it needs rules.  
    An organization can tolerate some members that contribute little or nothing to the group, but they can't tolerate for long those who refuse to follow rules, even though they insist they are members of the group and deserve all the benefits of membership.
    If a society, group, or organization is going to function, it must weed out those who refuse to follow the rules.  To many people today, that sounds like blasphemy.  How dare I suggest that anyone give up some individual rights to be part of a group.  Everything has a price.  The price of belonging to a group, whether it's a nation, church, club, business, whatever, is that you give up some individuality to get the benefits of group membership.  This doesn't mean you give up all individuality and become just a worker bee, but neither can everyone run amok doing whatever they want to and expect the society to continue for long.