Political correctness enables bigotry by trivializing offensive ideas.
If the objective is to call out genuinely dangerous and bigoted opinions when they are expressed, then political correctness is more of a hindrance than an asset.
The backlash against PC actually empowers bigots. By being overzealous, PC warriors are enabling bigotry by trivializing it. Being called a racist for having dreadlocks as a white person, or sexist for calling someone “Dear”, trivializes sexism and racism and weakens the denunciation of bigotry when it does genuinely occur. When severe racism and sexism does occur, it becomes more difficult to defend the victims and denounce the bigot without being accused of being a PC warrior, or a snowflake. It leads to a difficulty to clearly demark the difference between a 'microaggression' and serious discriminatory behaviour. A more measured view of political correctness would allow society to better confront dangerous opinions when they’re expressed.
When employed correctly, political correctness forces us to examine our speech and modify it in a positive way that prevents damage or harm done to others. At its core, it is not supposed to put perpetrators of 'micro offences' in the same box as bigots and those that hold deeply racist and sexist beliefs. A politically incorrect statement is not tantamount to hate speech. Nobody would suggest that everyone that uses the term 'obese' instead of 'people of size' hates plump people. Political correctness does not trivialize genuine examples of hate speech by conflating them with micro offences, it just forces us to adopt more inclusive patterns of language.
[P1] Political correctness makes it difficult to challenge more severe cases of bigotry and prejudice. [P2] Therefore, it does more harm than good.
[Rejecting P1] Political correctness has no impact on our ability to challenge bigotry. It merely helps us adopt more inclusive language.