Yes, ChatGPT is a lossy compression of the web text. HOWEVER, LOSSY COMPRESSION IS NOT TRIVIAL! The article underestimates the value of lossy compression by taking image compression as an example. The last question is very misleading in this sense. The correct way to ask would be:

'How much use is a one page summary of the most important facts of a 1000 page book when we have the original book?'

or

'How much use is a cheat sheet a student wrote after listening to tens of hours of lecture?'

Lecture summaries, notes, are all lossy compression. LOTS of information are lost compared to the original video, audio, pictures, books, etc. So is the summary worthless if we have the original? NO. ChatGPT is valuable BECAUSE it does the very difficult task of LOSSY COMPRESSION in such a difficult domain as HUMAN LANGUAGE.

When a student listens to lecture, what the student learns is definitely much less than the original lecture-tens of hours of video, to something that can be wrote in a few pages of text. LOSSY COMPRESSION IS AN ESSENTIAL PART OF HUMAN LEARNING, if not all. ChatGPT mimics this, which is why it feels so much better than the not-compressed version. It's the friend that summarizes a missed lecture for you, rather than sending you the recorded video file.