Why space opens up when an unskilled player spreads wide on the flank

‌It's because you can afford to defend them slowly.
If there were actual pressure, you wouldn't give them that much space...
But since the space opens up so wide, it feels like you can't afford not to give it.
So when you do give it... there's obviously nothing to do until the defender closes in,
and since they lack the ability to dribble past, it's difficult to pass the ball to other players once the defender approaches.
They just stay wide, receive the ball, and pass it off.
Because they are stretched wide, they can't even participate in the battle in the midfield,
and they just waste stamina running up and down the pitch for nothing.
I believe you need a certain level of skill if you're going to stay wide, avoid the scrap, and create space.
Otherwise, it's pointless.