Nobody ever wants to angrily stomp up the stairs or leave their house to knock on a neighbor's door and ask them to acknowledge that other people live near them. Having a friendly and respectful relationship with the people you share a block or building with can be fun and mututally beneficial, but it is frustrating when people assume their walls are made of soundproof steel. If you can hear others, others can hear you. That includes your music, 3 AM laughs, blaring television, tiny constantly-barking dogs, and screaming children. Of course, most reasonable people understand that everyone has to live their lives and a certain level of sound during waking hours is perfectly acceptable, but sometimes you have to put an end to the daily, four hour tap dancing sesson above you.
So, when an angry neighbor decided to consult the online courtroom of moral philosophy otherwise known as Reddit's "Am I the As*hole?" about the piercing, constant sound of their neighbor's crying baby, people were quick to offer advice.