The key difference between your car and YouTube is that YouTube (or Facebook or Twitter) makes part of new media that has reach far enough for commentary published on it to shape public discourse. This is especially big thing within young democracies for which new media is de facto mainstream media.

Our markets are usually regulated to make sure monopolies don't arise, and if they do, they may be forced to downscale, split or open market for competition.

This is not the case with major social media sites, that answer only to the mighty dollar.

I'll try another one.

It's more like you having a potluck, or cook-off, meaning anyone can come and join and contribute food.

But then someone prepares Surströmming, Hákarl or Shiokara, which is technically food (content) that someone might like. It will now smell all over your potluck and have a detrimental effect on peoples view of it. You have previously reserved the right to turn away participants, and you exercise that right.

That's a very bad analogy, you should stop.

The message of the grafitti is not what people care about, it's that it was painted in the first place.

Your analogy only works if you have a big sign outside your house saying "Please paint my car".

Don't misconstrue what is being said. Imagine the sign saying "Please paint my car but we reserve the rights to remove anything we want". That's essentially what the YouTube user license says.

Graffiti is done without permission. What exactly am I misconstruing? That's exactly why the analogy is so bad.

Many user-licenses forbid things like spreading "hateful" (I actually don't like that word) content. Some users post such content, thereby doing something which they had no permission for. When that content is removed, in compliance with the agreement, they call that censorship.

So my analogy still works.

The difference is that on YouTube some "graffiti" are permitted while others aren't whereas on my car, none are permitted.