Morality As a Limit
Ask not what your country can do for you: Ask what you can do for your country.
The concept of value requires a purpose and a beneficiary. It requires answers to the questions "Value to whom?" and "Value for what?". Collectivism is an answer to the first question. It says value to the collective, whether that's society, your tribe, your family, your nation, your race, your sex, or any other group or category you "belong" to. The standard of good is that which benefits the group.
At the root of this ethical standard is the belief that a collective is more than just individuals interacting together. It is the belief that the group is an entity itself, more important than the sum of the individuals. The individuals become secondary to the collective. Their well-being and even their lives are ignored if the group has something to gain. Individuals are not recognized. They are merely a tool for the group.
Collectivism is a form of anthropomorphism. It attempts to see a group of individuals as having a single identity similar to a person. The collective is claimed to have ideas, and can think. It has purpose, and it acts to achieve goals. It even has a personality, called culture. It claims to have moral rules the collective should follow. It claims to have collective rights, as well.
Since the collective is actually just individuals interacting, the collectivists have to change their views of individuals. They morally evaluate people according to the results of the collective. If the collective manages to accomplish something great like land on the moon, every individual is given equal credit. If a nation goes to war, everyone is to blame. And if an individual refuses to acknowledge the superiority of his collective, than he is a traitor and is eliminated. This is the result of collectivism.
Collectivism demands that the group be more important than the individual. It requires the individual to sacrifice himself for the alleged good of the group. Although different from altruism, collectivism complements it well. Altruism demands sacrifice for others, collectivism demands sacrifice for the group. Collectivism leads to altruism.