The purpose it serves is to free up FLOOR space. It's serving that purpose perfectly and the noise issue does not affect the neighbour in any way shape and form so all is good.
Why? What purpose does it serve other than taking up space?
I'd think the box it is sat upon would also serve as a resonator box, for extra vibration noise!... at least until the vibrations from the washer cause it to collapse.
I just think you are looking at the problem backwards by fixing symptoms rather than causes.
surely the correct solution to remove vibrations and free up floor space is to suspend the machine from the ceiling.
https://www.matousch.com/the-source-periphery
How the **** did you get a washing machine in the loft 😲
How the **** did you get a washing machine in the loft
A more pertinent question would be "why would you want to?"
