Some teachers in my department are consistently putting images from code in their slides and web pages. In this way they force students to retype the code inste

Some teachers in my department are consistently putting images from code in their slides and web pages. In this way they force students to retype the code instead of just copying-and-pasting it. Another case could be to make sure that the code always looks the same if you are going to put it in a Powerpoint presentation that you want to share/copy to a conference laptop. (However, if one does not need to embed videos, it's probably better to export a plain PDF.) Apart from these very specific cases, I agree with you: it is more useful to allow people to select the text.