There's more to it than just bladedness. Bladed angle is very easy to adjust. It's not difficult to switch from more bladed to less, at all. Wide or narrow, the functions stay the same, but there is a reason many choose to stand more bladed. You don't need to "teach" a boxer how to stand less bladed.
That angle may be the most easy, visible thing about it but that's not the most important difference by a longshot. The differences are there but to those who don't know the uses/functionality of it in the first place, the traits remain invisible. It's like a kid who's only hobby is pokemon trying to understand the subtleties of a diesel engine by a casual glance.
That's why boxing is so incredibly effective. It's abilities are hidden until you have a working grasp of them yourself. You can be hurt most by what you see and understand least. Boxing, by intentional design, is the most subtle and efficient striking art.