How was the open door policy good for all the european powers

The Open Door Policy is a term in foreign affairs initially used to refer to the United States policy established in the late 19th century and the early 20th century, as enunciated in Secretary of State John Hay's Open Door Note, dated September 6, 1899 and dispatched to the major European powers.[1] The policy proposed to keep China open to trade with all countries on an equal basis, keeping any one power from total control of the country, and calling upon all powers, within their spheres