Extremely cringe for several reasons.
1. It's one of those ideologies that attracts teenagers and young adults because it puts forth a simple, easy-to-grasp understanding of the world that runs against the mainstream. This means that it becomes 'baby's first totalizing political ideology', so it's associated with insufferable 18 year olds who think that they have the whole world figured out and can boil it down to a few dumb, autistic slogans.
2. It tends to infect other political movements, and then completely hamstrings them because it's a retarded ideology. A good example is the cold war fusionism right wing, which completely abandoned pursuing positions in federal bureaucracies or public schools because the government was icky. This is what allowed the left to run a long march through the institutions in the later 20th century basically uncontested. The idea that you should never take political action because then someone might take political action against you is mind-numbingly retarded when the other side has already been taking increasingly draconian political action against you for almost a century.
3. It's the kind of ideology that people in academia or think tanks/media enjoy (or people who have a comfortable inheritance), so it has an incredibly lionized view of the private sector that would be instantly dispelled by actually working in it. This makes them immediately insufferable to anyone in the private sector, who knows how incredibly fucked up and dysfunctional it is, and how retarded the 'captains of industry' and their managerial staff often are. And how the 'market' doesn't correct for any of that retardation most of the time.
4. 'Real capitalism has never been tried'. Libertarians will constantly make fun of commies for pulling this one, then go around and do the exact same thing, moving the goalposts any time you make a criticism of capitalism. It's even easier for libertarians to do this because, while communism is a shitshow once put into practice, it can win political victories and so actually gain a position of power. It has a record to critique. Libertarians doesn't have a record to critique because it's politically impotent, and so never wins any sort of victory that can translate into an effective libertarian political structure.
5. Not understanding how the structure of capitalism is itself perverse and often leads to bad outcomes, and so they get btfo by commies whenever they argue - because they have to autistically defend the perfection of capitalism, and look like weird losers who are stubborn and wrong about a bunch of stuff to any politically ambivalent audience which doesn't already agree with them. This is especially annoying because they walk away from these arguments thinking that they won, and getting slapped on the back by their libertarian buddies. But the measure of 'winning' a debate isn't in who has the most beautiful, internally consistent arguments, it's who convinces the audience to change their minds. And they seldom do that.
It's easy to win arguments against communists. You agree that capitalism has fucked up aspects, put forward an alternative plan to address that, and then point out how retarded their own ideology is and how often its fucked everything up. If you dig in your heals defending a flawed system you automatically lose.