One reason you shouldn't pretend otherwise, in particular, is that pretending you don't rely on other people is one easy way to fall into the wrong crowd. This is part of the reason there's an embarrassingly slippery slope from libertarian free speech arguments to Nazism.
Libertarians are committed to a vision of thought as a lonely, isolated endeavor; we're all supposed to be free, rational, unattached enlightenment brains, soaring above the herds of baah-ing sheeple and malevolent witch-hunters burning Galileo. We should ignore the distracting sweaty mobs, and determine the truth through beautiful reason by evaluating all available information with dispassionate Spockishness.
And that's where the Nazis come in. In the Spockish view, Nazism is just another contextless argument. Libertarians believe that Nazi arguments are bad arguments of course—but they know that because they listen carefully to Nazi arguments to suss out the badness. Free speech absolutists argue that we need to allow Nazi speech into the public sphere so we can refute it. Everything must be evaluated on its own merits; you can only arrive at the truth if you, independently, listen to all arguments and sift them each for yourself.
The problem here is that no one actually thinks like this. People aren't autonomous brains; they're people, who live in communities. In particular, Nazis don't just present their ideas dispassionately for the edification of free speech absolutists and libertarians. Nazis actively target marginalized people; they send them death threats. They send them rape threats. They stab them and drive cars at them when they can. The goal of Nazis is not to put their ideas forward for evaluation. It's to use speech, lies, and actions to drive marginalized people out of communities, not infrequently by murdering them.
Being in a community with Nazis is not safe for marginalized people. So, when Nazis show up in a community, lots of people say, "fuck you, Nazi. You're not welcome here."
But if you're a libertarian, this seems intolerant. We must listen to all people equally! How else can I make up my independent mind and evaluate the evidence!
So what happens? An independent thinker makes a big deal of talking to Nazis. Folks who aren't Nazis are appalled and frightened. They try to get independent thinker to stop talking to Nazis who are trying to kill them. They point out that they are going to have to stop talking to independent thinker, because talking to IT means coming in contact with Nazis, which is really dangerous.
IT gets more and more pissy. On the one hand, here are the Nazis, pleasantly talking to IT. On the other hand, there are these nasty anti-Nazis who are telling IT that IT's not allowed to carefully weigh arguments about whether or not to kill them. Quickly independent thinker starts to hang out more with the Nazis, and less with everyone else. The Nazis say the non-Nazis are irrational and mean—and hey, the independent thinker has to independently agree that those non-Nazis are sure being mean, and aren't rationally listening to Nazi arguments about how non-Nazis should be murdered in camps. Those Jews/black people, women/marginalized folks obviously are bad people; based on independent thinking those Nazis are onto something!
Eventually, independent thinker has created a community of Nazis—and when your community is composed of Nazis, and you're accountable to Nazis, then the people doing your thinking for you are Nazis, which means you're a Nazi too.
This doesn't happen to all independent thinkers (TM) by any means, but I've seen it happen to a couple on social media. And obviously, writ large, the rage against "political correctness" and the insistence that free speech means letting racists prattle from every platform helped legitimize Trump. When you reject all community, you effectively open your brain to the worst possible communities. If you aren't willing to choose a side, the worst side will choose you.