Although political correctness began as a courtesy, it has grown into a standard that harms civil discourse. While discussing controversial issues, people cannot speak with peace of mind. They fear being "canceled" simply because they are ignorant of popular terminology. Political correctness has grown from a simple courtesy to a harmful form of censorship.
This sort of censorship is unforgiving to those who may be politically incorrect but mean no harm to the party the statement was directed at.
Further, to establish politically correct standards for everyone is against the First Amendment of the Constitution, which guarantees free speech. In 1971, the Supreme Court ruled in Cohen v. California that it is constitutional to "use certain offensive words and phrases to convey political messages."
Politically correct standards would therefore not be a proper use of free speech for many people.