TL;DR -- There are way more offensive shows out there. South Park mocks the stereotypes that these offensive shows try to normalize, and encourages us to think critically about them.

There are plenty of shows

that are far

more

offensive.

The problem with these shows is that they normalized sexism, racism, homophobia, etc. and reinforced negative stereotypes that people internalized, thus polluting society. They often did this subtley, which made them slip under the radar for so long.

South Park is satire and mocks what these shows have normalized, and what people accept as "the natural order of things." It sets out to get us to think critically about these societal flaws and injustices. And yes, it sets out to shock and offend -- but with good reason. It's to draw attention to the show (and yes, to boost ratings), so that people are exposed to these issues and start to question what we have long held as "normal" in our society.