The reasons for American Independence were established throughout the colonies. It is hard to know exactly when and where they began. They were largely the result of a distant administration that had little real contact with or understanding of the people they theoretically ruled, and who used intermediaries who frequently took advantage of their official positions for their own personal gain. In other words, it resembled the present in many ways.
Several currents combined into the movement toward independence. The aristocracy, primarily in Virginia, resented being treated as second class citizens by their British contemporaries despite their factual equality (in wealth, ability, education, and family lines). Merchants resented the laws that protected English merchants against competition from their kin who happened to reside in America. Frontiersmen were upset about corrupt colonial governments that abused them and refused to enact necessary laws for their protection.
There were a number of protests against colonial misrule throughout the colonies over the years preceding. One of the most important was the Regulator movement from 1765 to 1771 in the Carolinas.
We seldom hear about the Tea Parties throughout the colonies - but they occurred in ports from South Carolina to Maine. Yet we only hear about the one in Boston.
But in Boston the leadership created a literary establishment, a hub of publication and opinion-making. While the people in other colonies did have universities and did publish their own books, they were more interested in building a new country than in writing about it - thus the Boston Brahmins (as they are known) pushed their own distortions on the public. At the time, it was widely known that many of their claims were false, but over time - especially as new immigrants came to America and were educated with the books written by these people - many came to believe this version of American history as it was the only one they were presented with.
Most of the ideas underpinning the American Revolution came from the Enlightenment tradition in Europe, and came via the educated Virginian aristocracy. Boston's chief contribution was in pushing the Virginians to insist on religious tolerance, and this because the Bostonians were infamous for their intolerance and for their persecution of anyone with ideas different from their own - again, much like the present. The state of Rhode Island, in fact, was founded by colonists fleeing religious persecution in Massachusetts.
After the people of Massachusetts and Connecticut acted treasonously during the War of 1812 (and this after being the first to insist on the war for their own benefit!), the Boston Brahmins began a long campaign libelling other sections of the united States, particularly the Southern states, in order to establish dominance. They were so successful that after the war many Northerners were surprised to learn that most Southerners could read and write, that they were observant Christians, and were civilized.
Of course, Harriet Beecher Stowe's infamous novel, "Uncle Tom's Cabin", was a complete fabrication. The author of this infamous book never even visited a Southern state until after the war. Despite that, the book was influential enough that some claimed it had caused the war.
So it is more than Boston newspapers that have a long history of fabrication - it is the whole Boston literary establishment. Newspapers are just one part of it.