There's all kinds of these artificial enhancements in aircraft. They range from "stick shakers" [0] (which cause the control stick/yoke to shake when the plane detects a near-stall) to yaw dampers (which counteract "Dutch Roll" in swept-wing planes) [1] to full-blown "you tell me what you want and I'll keep the plane from tumbling out of the sky" control systems for fighters [2]. There are also "flight envelope protection" systems which prevent pilots from overstressing aircraft. What's uncommon is for them to lack redundancy. Yeah, Boeing has much bigger problems than just MCAS.