Besides being easy to extend, there are also small general features that are very useful and I haven't found anywhere else, such as narrowing. And these small features can be combined and composed. For example, suppose you just learned you can use dired to rename a file, now whatever you have already learned to edit text can be used to mass rename files, which could be using macros, using multiple cursors, using a regex query and replace, etc.
A great example of this is this video https://youtu.be/w3krYEeqnyk?si=JKvVsgMO89DbCkhF
Besides being easy to extend, there are also small general features that are very useful and I haven't found anywhere else, such as narrowing. And these small features can be combined and composed. For example, suppose you just learned you can use dired to rename a file, now whatever you have already learned to edit text can be used to mass rename files, which could be using macros, using multiple cursors, using a regex query and replace, etc.