You seem to be under the erroneous assumption that human specialists and market makers actually caught falling knives in the past. Sure the rulebooks said they

You seem to be under the erroneous assumption that human specialists and market makers actually caught falling knives in the past. Sure the rulebooks said they were supposed to, but rules aren't reality. Black Monday is the classic example. Lots of phones were ringing and simply not getting picked up because they didn't want to deal with the orders. That's even worse than today. Unless you were on the right trading floors, you couldn't know what was happening and you couldn't cancel or enter new orders.