What's the deal with the legal introduction?

it either claims that the code is not resilient enough to stand on its feet without some liability safeguards or actually i cannot think of any other reason to start the book with such language. and what’s the deal with “don’t share with friends” stuff? i am pretty sure the same could be said in a less condescending manner.

please address my confusion. i am not trying to start an argument, but this is the first time i am greeted with such an intro. what the hell is going on?