You can already measure where the visitor's view is and notice the sections at which the visitor stares the most. The scenario you've given is also very simila

You can already measure where the visitor's view is and notice the sections at which the visitor stares the most. The scenario you've given is also very similar to a scenario in which the user opens the web page and then manually searches for "cancer". Or scrolls down rapidly until they notice the word "cancer" and then stops. I do that all the time for example. So I don't see how excluding such a feature protects the user in any way compared with the status quo.