GeneralNickshit posting aside this is just a stupid premise. Are there like 3 different circle jerks that are all permabanned that make it their life goal to ruin the experience for everyone else? Yes. But there are maybe 35 people total that fall into that category. The literal hundreds, if not thousands, of other players, are normal people looking to have some fun and are usually pretty chill. Whether it's a new player asking how to set up a team or someone who's been around forever, almost all of my interactions with other players are overwhelmingly positive.
... if you can accept that there will always be a certain tiny portion of the community who are only in it to ruin the experience for others, I assure you that you will see how good the community is considering this is a 17-year-old game. Hell, you think this is bad? Trying playing overwatch, valorant, csgo.
If you want to fully understand negativity in tf2 you kinda have to be somebody who doesn't fit in. Enough people bring that upon themselves that even the people who really don't deserve hate end up getting victim blamed/ostracized. Brock's posting is wacky for sure but i do think our scene could have a bit more awareness in regards to perpetuating negativity. Comp tf2 isn't really a safe haven or exemplar of sportsmanlike/friendly behavior like you think- its just immunized to the kind of banal toxicity that comes when people interact with randoms. Everybody knows everybody. The type of toxicity that festers in league/valorant/whatever are qualitatively pretty different so I wouldn't necessarily compare them to tf2. In any kind of small community, being disliked regardless of fairness has a way of following/clinging onto you in a kind of pervasive way that leaves you miserable, even well past the point of it being reasonable.
You wont see players around much who experienced this kinda stuff telling their stories cuz they usually just quit and move on. Just my 2c