As far as I have learned:
If you'll notice on that page, that 12000 grit is equivalent to 2 microns.
Micro-mesh have been around for a long time in the woodworking hobby. Their "grit" levels are based on the Japanese standard.
While 12000 grit (Japanese) may seem very fine, P4000 ggrit or 4000 grit Abralon (FEPA or European standard) is equal to about 3 microns. Trizact's white pad (Cerium oxide) is actually much finer than that, less than 1 micron.
To be honest, I have never tried the micro-mesh, even in my woodworking, because Abralon and other abrasives, seemed more practical and less expensive. Even Trizact is used on hard surfaced materials, like Corian and glass.
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"None are so blind as those who will not see."