At first I thought, what??
Also, if the machine is ever removed, it is possible to make a reasonable repair to the hole. Remove the concrete and plastic pipe, run round the hole with a 45 degree chamfer bit and make a tapered plug to suit. Drop in some polystyrene and glue in the plug.
If you make the concrete plinths, there is no reason they have to be flush with the floor. Some machines are very low; some people are tall.