He did more to improve the discourse of journalism, over the course of the 2000s, than pretty much any other single person in broadcasting. He went on bad shows and argued with them to their faces about why they were causing damage, mounting a passionate and detailed breakdown of what they were doing wrong (sometimes getting them cancelled as a result). He provided better coverage of a lot of issues (police brutality in the pre-BLM days comes to mind) than any "real" news. His show invented the technique -- still not common in broadcasting, for whatever stupid reason -- of playing the clip of a politician saying something had never happened or they never said something, and then right after that, playing the clip of them saying it. "Real" journalists actually had conversations with him about the technical setup that enabled The Daily Show to do that, which because of the nature of the technology at the time actually wasn't straightforward (as weird as that sounds today).
In the modern day, he got heavily involved in a fight for health care for 9/11 first responders, he had enough integrity to get cancelled from Apple because they wanted to dictate his coverage of China, and now, of course, he's directly doing interviews with important people where he (still) is doing a lot of the things he is saying he wishes the other media would do.