Here's why:

* Osmosis requires a semi-permeable membrane: Osmosis is the movement of water across a selectively permeable membrane from an area of high water concentration to an area of low water concentration. Dead cells lose the integrity of their cell membrane, making it no longer selectively permeable.

* Dead cells lack active transport: Osmosis is often coupled with active transport mechanisms within living cells to maintain osmotic balance. Dead cells lack the energy and machinery to perform active transport.

Therefore, while water movement might occur passively in dead cells due to concentration gradients, it wouldn't be considered true osmosis.