Every story is created in a manner that the author is comfortable with presenting to their audience. It is wholly their creation and their perspective on a world of their own devising.
Their own creations may represent their unique perspective but every narrative that has ever been presented to the world has been subject to both editors and publishing guidelines. A filter is applied to their work so that it can be presented to their audience.
One short-hand method for authors to add tone or apply a 'gritty-realism' to their work is to utilize elements of everyday life from gut-wrenching violence to sex scenes so detailed an artist could count the freckles to extensive use swearing that could put a sailor to shame. These elements bring the audience into a 'real world' and pull them in with their spell.
Or do they?
In many instances authors may use these elements as a means to apply realism to the world but are they really necessary? The power of writing is that it lets the audience take control with their imagination. The audience is what truly brings the piece to life. If too many of these elements are laced within the narrative what does it accomplish? Interestingly enough, not what one would think.
As these elements of 'gritty realism' are laced throughout the piece it may assist in world building but as the levels of these elements increase the author is actually decreasing their potential audience. In most instances of 'harsh language' it is actually superfluous. Much like adding extensive dialect to a piece, adding language is the same as repeating a detail. Not only can the audience already understand the details they may actually grow tired of it. This is why editors and publishers may filter these elements. They want a piece to reach as wide an audience as possible.
Adding 'gritty realism' to a piece can work really well but the levels of these elements will actually dictate the potential audience. Is it really wise to keep reducing the size of that audience?