The problem is that general discussion forums that emerged in the early days of the internet gave people a way to express non-conforming opinions that they never had before. Letters to the editor were only published if newspaper editors felt they were appropriate for their target audience. Speech on public streets can be and is regulated, so offensive speech can be censored for the "sake of the children". Many of those who came out of the closet built up the courage to do so only after finding so many others like themselves anonymously proclaiming themselves online.
Fast forward to today, and every news site has a comments section for every news story. But the fear of liability for tolerating bigotry or allowing cyber bullying has most of these mainstream news outlets deleting comments and even banning users for rather mild offensive speech or politically incorrect positions. Many other websites that allow comments selectively delete content that doesn't fall in line with their own ideology. This story just shows how the trend of private censorship, speech control, expression management - or whatever else you want to call it - is growing, and there are now fewer places where the general internet faring public can go to vent their opinion to a larger audience. When the wackos, weirdos, and non-conformists cannot find a public and open space to vent their delusional opinions and ideas, they are driven underground. This has two very negative effects: 1. They surround themselves with others that share their own crazy world view, reinforcing their perception that their view is rational, sane, and acceptable; and 2. they are cut off from mainstream society and with it the possibility that they could be exposed to logical challenges that might lead them to question their own delusions which could hopefully break the chain of insanity.
So in singular cases I have no problem when one website decides to impose stricter rules for comments from their contributors. But in aggregate it is harmful when such strict controls are so widely adopted that no one can hear what the lunatics have to say.