Why is abusive, negative content allowed?

"But make no mistake about it: the overall quality of the discourse in this forum has slowly degraded in the past two years or so (to the point of generating threads like this)".

I've been a member since 2003. After lurking for a while I chimed in as a newby with a question about whether cables really made a difference and, if so, why. What followed was a spirited debate among sincere, passionate hobbyists--some with strong technical backgrounds, others with years of experience swapping gear and experiences with others. The conversation never got personal, egos were restrained, ideas and opinions welcomed or politely rebutted. The thread went on for so long and went so far over my head that one of the participants, a cable manufacturer, sent me a 1M pair of ICs to try and keep so I could decide for myself. 

Subsequent posts followed a similar pattern. No judgement, ridicule or attitude directed at my inquiries or at others who made honest, gracious efforts to help educate and elevate the hobby. What has happened here is merely a reflection of what is going on across society. Narcissism, cruelty, egotism, and attitude reign supreme. I rarely read or post anymore--in the last few years the balance has tipped from occasional disappointment in the direction of certain threads to a nearly uniform pattern--post, torch, retaliate, repeat. The number of threads that offer enlightenment are few and far between. Many are just posturing and scoring points. Not sure what the answer is but if I were new to the site I would hesitate to join the fray. Too bad since most people predict this hobby is going to die and forums like these have the potential to attract new enthusiasts and expand interest. If only......

“Also interesting to note that of the top offenders I’ve seen... they aren’t here defending themselves. It’s a nice respite from them, actually. This is probably the only current thread where they aren’t spreading hate, condescension and general blather.”

Interesting observation indeed, at least this holds true for couple of posters with 20 plus posts each day. 

I never understood the parameters or standards by which we need to abide here.  A few weeks ago, I posted a hilarious thread, overly obvious not to be taken seriously.  I was dying to read the responses from the members.  And some did get through.  And sure enough, they were very funny.    But then there was one, one that got offended.  One little fragile flower that had to run and tell on me.  And sure enough, the thread was removed, even though there have been countless threads that involved very offensive and aggressive responses and behavior.   I just don't get it.  

"Analogy time:  if I owned a pizza shop and had someone standing in front of my door telling all my customers that pizza all over the world sucks, and that they are stupid for eating pizza, and that no one can really make a good pizza, I’d call the cops on him and have him removed."
Depending on the country, you might be disappointed to find that if he is in public space, that you cannot do that!  Just because you don't like an opinion does not legally mean that it cannot be spoken.

(And no, I am not defending truly abusive posts, but rather the fact that I feel that a lot of folks are way too intolerant, and instead of simply skipping that content or ignoring that user, they choose to attempt to dominate that individual with *their* point of view, which may or may not be any more or less valid.   My view:  Let 'em speak, and skip/block what you can't cope with . . . ).