Can I use 3/4" MDF platform that is 27" x 27" as an intermediate base platform between a washing machine that will be grounded to the MDF platform at the 4 corners by the leveling legs. And, below the MDF platform, will be 4 vibration damping spring posts at the same corners resting on top of the ground floor.
Thus, the MDF will just be a sandwich filling transition between the leveling legs of the washing machine and the spring damper posts below.
I'd want to look at the details of the tops of the spring posts, how they attach to the shelf, and whether they can be positioned directly under the machine's feet.
But MDF really doesn't like getting wet; even repeated slight wetting is going to degrade it over time. And there are sometimes drip around washing machines. So I'd use a more water-resistant material, probably with a waterproof surface finish as well.
If the height of the posts is more than a few inches, cross-bracing will be necessary given that it's a heavy moving load.
