No. The spacers are an integral part of the system; the outside edges of the top cap push down on the spacers or the stem, not on the steerer tube. The adjustable stem here slides over the steerer tube in the same way the spacers do, and functions as the combination of spacers, stem, and top cap. It would be impossible to get the stem over the existing top cap, and if you could you wouldn't be able to achieve proper compression of the bearings.