The problem of Reddit is the opposite, that they arbitrarily ban subreddits, like the ones you cited.
The second problem of Reddit is that whoever gets to first register a subreddit gets to arbitrarily censor it, so whoever happened to register, let's say, "javascript" first, now gets to be a dictator of JavaScript discourse, and the Reddit admins in this case, instead, do nothing in response to complaints.
The third problem is that any competitor site is going to be unsuccessful due to network effects except at attracting the banned Reddit communities, so you get a site that is full of trolls and controversial communities without balance from the rest of society.
While true, this is also the kind of thinking that gets you populist leaders like Donald Trump. You can drive out the opinions of everybody you disagree with, everywhere, while chanting that "you have free speech, just not here!", but as long as we hang on to the concept of representative democracy, those people are still participating in the political process, and they're bound to remember that the ballot box is the only place that they're permitted to express unapproved viewpoints.
How on earth is encouraging people to express views that, followed through, would result in direct harm to people, supposed to prevent those views from being put into policy or resulting in hate crime? The actual problem isn't that they're expressing those views - it's that they have them in the first place. Consider solving that, rather than rushing to the aid of people who'd rather have me dead.
To be fair to reddit, they're doomed either way. A lot of the subreddits that have been banned haven't been banned because of their content but because they were involved in doxing people. Some examples include /r/incels and /r/altright. There are subreddits remaining that most people would consider distasteful and maybe even bannable like /r/watchpeopledie that stay because they follow the rules. I agree with your points though.
The problem of Reddit is the opposite, that they arbitrarily ban subreddits, like the ones you cited.
The second problem of Reddit is that whoever gets to first register a subreddit gets to arbitrarily censor it, so whoever happened to register, let's say, "javascript" first, now gets to be a dictator of JavaScript discourse, and the Reddit admins in this case, instead, do nothing in response to complaints.
The third problem is that any competitor site is going to be unsuccessful due to network effects except at attracting the banned Reddit communities, so you get a site that is full of trolls and controversial communities without balance from the rest of society.