The reason for this is that the tree organizes the program into pieces that are (mostly) semantically meaningful, whereas representing the program as a string d

The reason for this is that the tree organizes the program into pieces that are (mostly) semantically meaningful, whereas representing the program as a string doesn't. It's the exact same phenomenon that makes it easier to manipulate HTML correctly using a DOM rather than with regular expressions. Mind. Blown. Your whole comment is incredible. I've never thought about it this way or realized what the value proposition was. Thanks!