I observed the following while trying to produce scalable controls, albeit simple. A pitiful example: boolean, importing simple wmf for true and false with circular gradients. The original svgs are 5kB each, converted to wmf makes 2x65kB, the saved control blows to 278kB. The circle scales, but doesn't antialias (a known fact); the mask is square, albeit in the svg the exterior of the circle is set as transparent (ported to linux it shows glossy white corners, transparency not supported, also known).
In contrast, customising a silver led (which has a native vertical circular shape with a vertical color gradient, and a native decal)... 5kB.
Undocumented and inaccessible PICC bonuses, I guess...
For a circle with a border, fine; but if I desired complex shapes, beyond what one could achieve copy-pasting any of the given round, triangular and rectangular decorations - too bad.
Passing by, it is apparent that there are many examples of controls using many native scalable polygonal shapes (Classic Toggle Switches and DSC pipes and pumps to name some), but nothing to be done about.