Punk rock as a genre has always been anti–establishment, with many songs offering commentary on political and social issues. However, bands of the '80s and '90s would never be able to produce some of the offensive songs they did in the political climate of today.
With the rise of the internet, PC culture has taken off. Angry keyboard warriors will take to Twitter, sharing content they deem offensive, and thereby inciting tens, hundreds, sometimes even thousands of others to decry the content as well.
Without the internet, these songs were not as easily disseminated: music and music commentary are now available to anyone with internet access. If Minor Threat’s "Guilty Of Being White" came out today, there would no doubt be a much larger outrage than there was at the original release date of 1981, not only because this type of outlook was more acceptable at the time, but because non–radio songs just didn’t have the same reach. Today, all it takes is one upset person with a social media account for a song and its criticisms to go viral.
The main problem for these old punk songs isn’t that PC culture is inherently liberal: punk rock features a range of political views. Instead, the issue lies in the way punk songs tackled topics.
"Slip It In" by Black Flag tells a story about a woman who originally rejected a man’s advances, saying that she had a boyfriend, that she had too much to drink, and that she flat out “[didn't] want it,” but, at the end of the song, she gives in. The intent of the song was to point out how women like sex just as much as men do, but they are considered whores if they don’t at least pretend not to want it. However, the lyrics reference slipping something into the girl's drink and the fact that she wants it even though she says she doesn’t, giving the song an outward appearance of normalizing rape.
This back–handed way of addressing touchy issues caused accusations that Black Flag was sexist at the time. However, the backlash never went viral. Today, there's been a lot of controversy around victim blaming and rape culture, and I believe that, coupled with the ease of sharing across the web, this song would have much worse negative press than in just the few punk publications that discussed this song.
Punk rock bands also had no problem making non–PC jokes. The Dead Milkmen did a couple songs on mental illness, including "Takin Retards to the Zoo" and "Take Me to the Specialist." The latter focused on a schizophrenic who would take “pretty pills” from the specialist and ask if the specialist had any power tools, to which the track responded with drilling noises for a good portion of the song. The same band also did a song called "Bleach Boys" that was about a group of friends that drank bleach instead of drinking or smoking pot.
While people today are somewhat lenient with the sexism and violence in a lot of rap music, I think most people who would pose these kind of complaints would draw the line at mocking mental illness or suicide. While many people still find these songs and more offensive humor funny, there's definitely a higher expectation of being considerate towards these more sensitive subjects. With the mob mentality of the internet, I have no doubt that if a few people showed outrage at these songs, it’s likely that a lot more people would jump on the bandwagon.