Yes, I think most juiciness is actually fat/oil, not water. Pretty sure one of those more serious food blogs measured it once. This is why basting in fat is important sometimes.

I was gifted some leftover thin wagyu cuts recently. I cooked them through because they have so much fat they're still tender, and the brown adds flavour. It just had to render enough. I guess they were technically "well done" but perfect for me, as someone who prefers medium on typical steak.