Valid question, I suppose.
Afterall, people ask me the question a lot.
Yes... yes they do.

People like to psychoanalyse... and when I do something that gets to them, they like to psychoanalyse me. Its not like it achieves anything tangible, but it seems to give them some small sense of purpose or something I guess.

Anyway, back to the question...

Basically because theres a lot of fucked up people in the world
I'm probably one of them, but thats not really relevant.
There are a lot of fucked up people who don't matter, and then a small few that I sometimes think do matter. I couldn't care less about those that don't, except in circumstances where they might influence those who do... and that is problematic.
Not clear enough?
Lets put it this way...
Many people on the Internet get their kicks directly at the expense of other people. This effect is self-propagating. This means that people showing this mentality cause others in turn to show the same mentality. Its like an infectious disease. More than that, if you get enough worthless fucktards laughing at something and saying its crap for nothing but its own sake, theres always the possibility that someone who actually matters might be swayed by these hollow statements and allow their opinions to be swayed by such things.
The main difference between worthless fucktards and people who matter is that the opinions of the latter are irrelevant, while the opinions of the former can make a difference.
So needless to say, regardless of how irrelevant a bunch of lifeless fools might take joy in proverbially prodding people may be, it can have a negative effect on things. Since there isn't much that can be done to remove their influence, the only applicable defence is simply to take away that which they need to survive.

Its not an easy task by any means.
Some fools honestly spend their time practicing in order to be able to individually pick out anything and spend a long time saying its crap, and if they say it enough it can practically become Internet Law in its degree of acceptance.
Perhaps the only way to go about it, besides to take away anything that its actually worth mocking, is simply not to care at all. This doesn't always work, but one has to make do with what one has available. Afterall, I'm no cracker. Its actually made difficult when there are people who matter whose opinions are swayed, and perhaps the best way to deal with that is not to care about them either.

Afterall, despite all the other things I got horribly wrong in my youth, I had worked out one thing correctly a decade ago:

Its all quite meaningless really.