They're getting downvoted because what they're saying is like the vehicular equivalent of asking a victim of sexual assault what they were wearing.
Cyclists (and pedestrians) are vulnerable road users around cars. Of course they should exercise caution! No one's saying they shouldn't! But going around and telling people biking or walking they ought to be careful isn't the solution to the actual issue; that being the dangers of cars.
We need public transit, safe cycling/pedestrian infrastructure, car-free areas, and streets that aren't designed like highways going through our cities. No amount of vigilance by vulnerable road users can surmount the utter state of our car-centric infrastructure and a single moment of distraction from someone driving.
Yeah, that's victim-blaming. I'm not saying caution is a bad thing, of course it isn't. But what this kind of rhetoric does is frame things like the responsibility of the victims. That's why the other commenter got downvoted.