general background noise. BB is posited on our universe being controlled by gravity. It pretty much ignores the stronger forces including magnetism and electricity. Those forces play a much greater role in shaping the universe than General Relativity claims. Magnetism and electricity generate radio waves. Our whole universe is filled with transmitters that have radiated radio waves forever: background noise.
The cosmic microwave background is not noise. It happens at a specific frequency and is detectable above the background noise caused by the effects you list. Gravity is the dominant force on cosmological scales. Electromagnetism is very weak on that scale and has virtually effect on the masses (i.e. stars, planets, comets, galaxies, dust clouds). An understanding of basic physics would let you know this.