There is open stance, closed stance, and natural stance.
Natural stance on the forehand is practically open stance, unless you are in a hurry and hitting on a mad run.
Natural stance for the two-handed backhand is practically open stance.
Natural stance for the one-handed backhand is practically very closed stance.
Why are all these so? Because they better align the body to produce a more natural, more efficient, more controlled, and at the same time more powerful shot with less effort (unless you play tennis like baseball, where power, not control, is emphasized, or perhaps bunting the ball at slow speeds).
Tennis is not baseball, golf or cricket. It has it’s own movement, as natural as going shopping or running to catch your cat or your dog.
Which also applies to your thought level. No thought, just looking and feeling.
In simpler words, Find the Ball, Feel the Ball (brushing it up and across), Finish the stroke. That’s all. The rest, like a walk in the park!