This was in around 2012, maybe attitudes have changed. This isn't my thread, but shows what responses to the question were like at the time: https://discussions.apple.com/thread/2805582
You only have to go a few responses into that thread to get an explanation that the action of closing the lid will trigger sleep, but an external keyboard and mouse will wake it back up, allowing for the machine to be used while closed. You may not have originally intended to make the distinction between having the lid closed vs. the process of closing the lid, but it's clearly the former you were worried about, and that use case has always been supported.
