SharkFart86 t1_jb203b1 wrote

What you’re asking is kind of a weird question, you can use anything you want as your reference frame. The CMB is often used as the reference frame because it has some convenient qualities that make it more a “fair” reference in cosmology, but there isn’t anything inherent about it that makes it more absolute than any other frame of reference.

And keep in mind that the reference frame matters within the context of the subject. Using CMB as a reference in regards to the orbit of the planets in our solar system makes way less sense than using the sun as the frame of reference. The frame of reference should be whatever makes the model clearer to accurately understand. The CMB works great when looking at the movement or rotation of galaxies, because otherwise those values are very difficult to describe in a clear way.