I for one would be OK with a machine learning model that's been trained using my data. I wouldn't demand that it be "re-trained" just because I asked for my history to be deleted. I think most people, given an explanation of what a machine learning model is, would be fine with this.
The clear history thing is about personally identifiable information though. It's not having your information dangling around after you leave Facebook. It's having the option to delete your shadow profile.
Throughout all the hearings, FB execs have been very wishy-washy about how they handle your browsing history, particularly what they collect outside of FB properties.
People should continue to call them out on this until they get their act together.