It is often quicker and less expensive to use a shim, a thin piece of metal or composite, to level a machine tool or make components fit together, than grinding and machining to make the same mechanical adjustments. Shims act like those folded pieces of paper people place under table legs to prevent the table from wobbling. They are also used to quell vibrations and silence noisy equipment. But laminated shims are more versatile and economical than slivers of paper or machined wedges.
Laminated shims make life easier for designers and machine operators, as long as they're properly specified.