Maybe your public school experience was mostly decent, but for a lot of people it's hell and it actively breeds misanthropy. You can learn to deal with stupid and difficult people without being exposed to soul poisoning doses of both.
Research shows that people learn well when there is the right amount of stress, and the right challenge. If the stress and challenge exceeds that amount it can quickly become destructive, which is what we see in your typical public school for any child who isn't primarily concerned with "fitting in."
At best, public school is useful. At worst, it's a massive waste of time and absolutely destructive to a young psyche. You can expose your children to that massive asymmetry, but it's not necessary, people who cared got along just fine before public education, it's really there to uplift the lowest common denominator.
"Fitting in" is no small thing. The world would be better today if more people had the ability to empathize with someone not-them, sufficiently adjust their own way of interacting to put others at ease, and generally be less abrasive and fragile.
And if we want to talk in absolutes...
At best, public school provides an opportunity to learn socialization that cannot be replicated in a home environment.
The problem with this "fitting in" narrative is that as adults we don't care about it so much, people enjoy meeting new and unusual people (as long as they're baseline socially functional), there's a huge social stigma against being bigoted so basically everyone views adult bullies as worthless assholes and the cops will arrest people for much less than bullies get away with on the school yard every day even in the face of repeated parental protest.
I would say that much of adult society still runs on "fitting in" (e.g. social groups, corporate hierarchies), ergo being able to do it deftly is a huge life skill.
There's definitely a stigma around adults engaging in specific types of bullying (physical) and bigotry (e.g. protected classes), but society as a whole rewards more subtle bullying (political power dynamics) and ignores subtle bigotry (e.g. caste, microaggression).
The point of socialization, and indeed bullying itself, in school is in no small party to teach everyone (bully and bullied) what acceptable and unacceptable forms are.
Absent that, you either get people who are worse bullies (because they never learned where the line was) or are fragile (because they never learned where the "I should/shouldn't be able to handle this uncomfortable thing" line is).
Getting knocked down then kicked every day at recess, cowering and begging for them to stop, solely because of the color of my skin, while children laughed at my misfortune, until the teacher eventually waddled over to save me was not, in fact, a great gift for me.
You can push anything to an extreme to make it bad. I'm sorry the adults around you failed you is all I can say. It doesn't mean school is a bad idea, or that going through moderate levels of crap doesn't build one's character. There's a point where adversity turns into actual abuse and that's when grown ups should support kids, either in school or in a pod or wherever.
Reality is mostly segregated. It's only in artificial environments where you have no recourse to avoid horrible people (or people that are horrible to you).
You probably was in the your tolerance margin to say that.
But I've been to 11 schools, including private ones and ones from very poor and violent places. And there are situation where the only lesson you learn is how much people can destroy you.