Spin accumulation is a crucial but imprecise concept in spintronics., the science that strives to harness the electron spin for the benefit of information and communication technology. In metal-based spintronics it is characterized in terms of semiclassical distribution functions. In semiconductors with a strong spin-orbit coupling the spin accumulation is instead described as superpositions of coherent eigenstates. Here we present theoretical arguments that both views of the spin accumulation can be reconciled by taking into account the electron-electron interaction: a sufficiently strong self-consistent exchange field reduces a spin accumulation to a chemical potential difference between the two spin bands even in the presence of spin-orbit coupling. We demonstrate the idea on a clean two-dimensional electron gas (2DEG) by showing how the exchange field protects a spin accumulation from dephasing.