Individualism is nothing but the creed that truths can be perceived by individuals, and that by comparing notes, we can more consistently and accurately approach the useful, which is to say the true.
Opposed to it is, and can only be, dogma, which is to say “truths” articulated by specific individuals–named or unnamed–and codifed by those in power into what is supposed to be consensus truth, a truth that is “out there” rather than one that arose in specific times and places.
For example, the Catholic Church was anti-individualist in the Middle Ages, and remains largely so to this very day. There is a Church creed that is superior to all individuals. If you are in the Church, you must accept Church doctrines. Period.
On the other side we have various totalitarianisms. No doubt one of the reasons Mussolini found Keynes so attractive was his rejection of individualism. Fascism is a system in which truth, per se, is conflated with the judgement of the Leader. No other truths can exist. They are suppressed by whatever means are necessary, which include mainly threat of force, but actual force as needed.
Liberalism, as I use the term, is the only political system consistent with individualism, since liberty and individualism go hand in glove.
Conversely, no matter what words surround the claim, any argument that individualism is counter-productive in any way is necessarily a call for tyranny.
To be clear, there is nothing in the creed “you can make up your own mind” that prevents charity, kindness, altruism, and all the other ooey-gooey things that Leftists claim to care about, and the opposites of which they consistently practice.
There is no society so stable it cannot be wrecked by enough Leftists trying to “help” it.