I've never heard of this obstructing vision, but I was first to say an O/U is more similar to your line of sight than the sxs. It was more tongue in cheek
I just find O/U more pleasing to my eye.
Just know if a recreational shooter or expert shotgunner uses a single eye obstruction, it's because they personally don't suffer an issue that is the norm for anyone with vision correction (contacts, laser, glasses) when they eyes are not both degraded equally. The consequence of an obstruction as mentioned is motion sickness which leads to headaches, throwing up, etc.
This is more normal than not for someone with vision correction.