While wearing a skate helmet I guess the full helmet meant a real integral one.

Compare any full face helmet (a motorcycle one for example) with whatever people wear for these (or for bicycles) to know why that would help.

Certainly a bike helmet.

1. Doesn't do a great job protecting the face or the side of the head;

2. Not designed for motorized vehicles, it can't absorb enough the kind of forces involved in these incidents.

You need a full face helmet, designed for motorized vehicles.

A motorcycle one is great, but probably an overkill (no pun intended).

There are good downhill helmets that can do the job well enough. Fox and Leatt are trustworthy brands. There are other good ones. It should be obvious, but don't trust Chinese brands.

- Most motorcycle helmets sold in the US are inadequate DOT helmets. ECE 22.05/22.06 helmets are literally 50 years ahead of the DOT standard, but you have to specifically seek one out in the US to get one.

- Most people purchase helmets in too large a size.

- Many people do not correctly adjust the helmet straps.

The Verge Article states three of the deaths occurred with riders not wearing helmets.

They changed the article after I got the quote from there. You can see the original quote ("The deaths came as a result of head trauma, with at least three of the accidents happening with the rider in a helmet") in Google Search results, but if you click on the article, the sentence isn't there anymore