Because the rate of new users getting scammed would be ridiculous otherwise.
Why? Explain please. I think that this is a baseless statement. Example, I'm here since 06 December 2015, you are here since 17 April 2013 and you are in DT1. When I created an account, no one told me that you personally would protect me from scammers. Am I right? I even know that you are exist
.If I were fooled by a scammer, only I would be responsible and I think it's right.
So, why so many years I "trusted" you by default? ("You", in the context of DT1)
That is nonsense that can't be applied to this.
Sorry, I will repeat myself, why? Could you explain how you see this? I can. I never trust someone by default. I know that there are many good people on this forum, but still, by default I don't trust anyone. I will check everything by myself. At least, I need to do my own research. But, by default -- never. Who are you going to trade with, some random that never did paypal-to-btc or someone who has 100+ such succesful changes? Oh right, don't trust verify the 0-trade-newbie offering reversible methods of payment. 
<- shows how absurd your attempt is.
I see your point, and the answer is -- the escrow. <- shows how absurd your attempt is.Yeah, "Who you can to trust if you do not trust anyone?", but still, if an escrow have a thread (not self-moderated) and there is a lot of feedbacks, so after checking these feedback and the account owners I will make my decision to work with that person or not.