The biggest surprise to me and to many, a big "faux pas" was that they were shooting with the little pop-up flashes on their Canon's. Let me clarify, they were not using the pop-up flashes to trigger off-camera flash units, they were using the pop-up flashes as their main lighting source.
I thought it was known within the professional, semi-professional and amateur photography circles that the use of pop-up flashes were a major "no-no" other than as triggers for additional lights. Using them for any kind of main lighting is pretty much guaranteed to provide the following:
- harsh illumination of the subject
- hard, sharp shadows
- unflattering lighting
- high chance of flare due to the light being so close to the lens
To put it into context, the small pop-up flash on most consumer cameras can be likened to a spotlight, whereas what you want for most types of photography is more of a floodlight. Having a wider spread of light is much more flattering on your subject as it reduces harsh shadows and doesn't "wash out" peoples complexions.
There's a reason why the main professional cameras from Nikon and Canon do not have pop-up flashes - they're unwanted. Speedlights and small studio strobes are the things to use for portable light sources and they are kept away from the lens as much as possible. At a minimum, when Speedlights are used on-camera, they are usually used with either a diffuser (of some description) or a bounce card to provide a softer, wider spread of light.
Unfortunately there seems to be too many photographers with little to no experience in using flash in their work. Working by natural, available light is all well and good when it's available but it's also unpredictable - and also usually needs some modification via diffusers and reflectors to provide even and flattering light. Flash on the other hand is eminently controllable and can be used either as the main source of light or as a secondary source. Many top professionals use flash in this manner and there are a plethora of books and courses out there that cover this topic. Above all else, the one thing a photographer needs to know and understand is LIGHT.