Expert?
All being in combat makes you an expert in is how you handled what it was that you went through. It may, or may not have any applicibility to anything else.
I knew a guy (he's gone now
) who jumped into St Mere Eglise in Normandy, and also went through the Bulge at Bastogne. Another who did multiple tours in Vietnam. Neither one felt that made them an expert on how to clear a block in the sandbox. While some basics apply the details are just too different.
My son spent time in the desert over there, and while he has some valid observations, doesn't think he's much of an expert in combat.
There are a lot of firearms experts who have never personally fought with the guns they know alot about. There are alot of combat "experts" that don't know much about firearms, beyond basic use and maint. So what?
One picture of someone firing a burst at something or at nothing means squat. Every fighting force, regular or irregular has some people in it that when they get into combat, do not aim, or follow the other basic rules of marksmanship. This has always been true, and likely always will be.
And even if your force is hand picked, the best of the best of the best, SIR!, there will be times when suppressive fire is useful, and precise aiming is not. Take a pic at that moment, and it looks like spray and pray is the way the "experts" do it.
I have heard from many people that a common attitude in the Middle East is "the bullet will hit if Allah wills it..." and they generally don't go much beyond that in terms of individual marksmanship. But there are exceptions...
Some of the "internet experts" do know what they are talking about. So do some of the people who have been in combat. Many don't, but think they do. Been that way along time, probably always will be...