Not 100% true. Maybe for a rimless tank. But most traditional tanks that have trim on the bottom. You'll notice that only the trim touches the stand. So even if your stand isn't solid base where the tank sits. It will still benefit from styrofoam and only the edges touch anyways. The styrofoam will settle and help take any imperfections out of the stand/tank and allow it to sit more level. Won't solve a large 1/4" spacing. But will help either way.
Unless you're 100% sure your floor, stand and tank are true and level. I'm a firm believer in using Styrofoam in all installs
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