Patti, they probably do that in some of the insanely versatile chairs for the elderly and disabled.  That would be a minor modification  compared to chairs which can elevate you to a standing position at the push of a switch.

I always imagine these things suddenly having a surge of energy and flinging the poor sod across the room.

Or imagine the well-bred older gent who usually stands up when a lady enters to greet her.  Instead he gets flung at her in what looks like a violent assault, ending up with them both of the floor, or bouncing off a wall.