A shop workbench is often bolted to the wall or floor and built from thick lumber or a steel frame, so the real job is disassembly, not lifting. Clearing the vise and any power strips first keeps you from carrying a pinch point.
Pro tip: A solid butcher-block top is usually the heaviest single piece in a garage; two people carrying it flat, not on edge, is far more stable.
Watch out: Never carry a workbench with the vise still attached; the extra off-center weight can tip the whole piece during a stair carry.