The reversible magnetization M(T,H) in the mixed state of the quasi-two-dimensional superconductor Bi₂Sr₂CaCu₂O₈ appears to factorize into a product f(T)g(H). It was recently argued that this implies a puzzling temperature-independent critical field Hc2, at least in the region where scaling is observed. We propose an alternative explanation in which this scaling property is approximate and results from the presence of vortex fluctuations, keeping a conventional temperature dependence for Hc2(T). New data in the BiSrCaCuO (2212) and TlBaCaCuO (2201, 2212) systems that obey to a good approximation the factorization M(T,H)=f(T)g(H) are presented.