Quite a number of WWII aircraft had fabric covered surfaces. One thing that happened to many of them was an upgrade from fabric to "solid covering". Their surface response and overall speed increased when that happened. Those two improvements suggest the skin texture and shape caused problems.

That suggestion suggests the ribs sticking into the boundary layer was not done on purpose.

The last suggestion suggests the orientation of the surface ribs was not based on aerodynamic considerations.

Needless to say, fabric covering had been around before WWII, and rib orientation probably had not ever been considered as significant aerodynamically until then.