COMPLETELY, totally, absolutely, 100% false.
100% false, except for Lexington & Concord, and the campaigns of Francis Marion (The Swamp Fox), Andrew Pickens, Thomas Sumter and Nathaniel Greene. In fact, it was Greene's use of guerilla tactics that drove Cornwallis back to Yorktown, leading to Cornwallis's defeat.
True enough, most of the major battles were fought European style. Washington was not a big fan of guerilla tactics, but those tactics were a significant part winning the war.
So, "100% false" is really 100% false.