So on the Hardest Difficulty it's better to just go guns blazing instead of strategically moving throughout the level.
Gotcha
That's what you don't get, moving around the level strategically
doesn't mean "stealth" only. You're conflating strategy and stealth as the same thing. You said yourself that you can't sit in cover and shoot everything in safety.
You gotta move around so that's the strategy. The game is Uncharted, not splinter cell. You can still utilize strategy that involves some sort of stealth versus running straight into enemies blind firing and drop kicking to victory which
will get you killed in some parts of the game. Hell, every encounter is not even the same so you can't make a blanket statement like "it's better to go guns blazing" when that's not applicable to every encounter.
Even when you're detected, you can run away and temporarily hide,
that's all strategy. In past Uncharted games, once they saw you, you pretty much had to hide behind over and pop and shoot till they stopped coming. In here, the area is so big that they'll flank you. I for example try to take out bigger guys with shotguns/snipers quietly and then go guns blazing with the regular dudes but that all involves some degree of mobility of which requires strategy. You're not standing there in full view just shooting everybody on some Resident Evil shyt.
you gotta mix it up. I'm not understanding what's the confusion here.
Strategy =/= Stealth.