That's because whoever has made that claim is more often than not trying to justify something incredibly sexist or racist or otherwise offensive and inappropriate. They minimise the wrongness of the offending statement by dismissing any objection to it as "political correctness gone mad" or some such.
But sometimes, political correctness does go mad.
From Canada's National Post:
Sumo suits, the plastic novelties that can transform a skinny sports fan into a comically unstable sphere for the delight of a stadium audience, are racist and dehumanizing instruments of oppression, according to the student government of Queen's University.
They "appropriate an aspect of Japanese culture," turn a racial identity into a "costume," and "devalue an ancient and respected Japanese sport, which is rich in history and cultural tradition." They also "fail to capture the deeply embedded histories of violent and subversive oppression that a group has faced."
The Alma Mater Society yesterday published a two-page apology and cancelled a food-bank fundraiser scheduled for today, which was to feature two Sumo suits. The letter scolds the student government's own executive for "marginalizing members of the Queen's community" and failing to "critically consider the racist meaning behind [the fundraiser]."
It also vows to discourage other campus groups from using the suits, owned by the school's athletic department.
I mean, seriously? Are the people who complained about the "racist" nature of the sumo suits actually Japanese? Was there more than one of them?
A classic example of this kind of thing was British banks deciding to no longer give out piggy banks to encourage saving, since they figured it was insensitive to Muslims, for whom the pig is a filthy animal. This is despite the vast majority of British Muslims probably not caring in the slightest - I mean, its not an actual pig, so it's probably not filthy. The result was added resentment towards Muslims - since the piggy bank thing was taken as a sign of them imposing their values insensitively on the wider society - even though barely a handful of Muslims even wanted that decision made.
There is ACTUAL racism going on in this world. Plenty of it, in fact, and when we see it, it needs to be called out and dealt with. The problem with politically correct over-sensitivity and being too keen to call things racist, is that it actually undermines the struggle against racism. (The same applies to sexism, homophobia and other social ills.)
When we make a fuss over something that is really not worth fussing over and label it racist, the term "racist" soon becomes devalued. Soon people start to think, "Well, everything is racist now." Then they start thinking that concern about racism as a whole is just a fuss over nothing. Which then enables others to proudly make racist statements because anyone condemning them is just being too politically correct, and shouldn't be taken seriously.
So to the student government at Queens University, while we appreciate your concern at being respectful to Japanese people and their culture, you need to lighten the hell up and focus on real issues.