I think there are lots of dangers in the world (traffic, carbon monoxide, broken glass, predatory strangers, bird flu, predatory friends and relations, dangerous dogs, escaped leopards, escalators, complications from chicken pox, terrorists, fire, the Ebola virus, open water, possibility of suddenly developing a life-threatening allergy). Each of these has a complicated web of factors how likely is it, in the world in general, to be a problem? How likely is it, specifically, to be a problem for your child? How serious are the likely consequences if the Bad Thing happens? What steps can be taken against it? How easy is it for a child to avoid the risky situation or to reduce the risk? How do you personally feel about it (it's hard to factor out emotional responses, no matter how illogical) personal experiences may factor in here?
Each of us has to consider all of these, and our individual children, and decide what messages it is most helpful to give our children. So, for example, I suspect that we'd all warn them regularly about traffic but would be unlikely to make a big deal out of the risk of Ebola or escaped leopards unless there were particular local circumstances that warrant it. What we say about any of the others is going to vary.
I don't think it's helpful to mock others for their choices, whether that choice is to pick one of those dangers and make a big deal out of it with their children or not to dwell on that danger at this stage in their child's development because after due consideration of all the factors they don't consider it to be appropriate. We're not all going to agree, of course, just as we're not going to agree on a whole host of parenting issues, but the fact that someone disagrees with you doesn't mean that they haven't thought carefully about the question or that it's OK to abuse them for it.