I must differ.
Although the twisting moment found on swept wings, when they flex in flight, is by far the most powerful, it is not the only torsional stress applied to a wing in flight.
If you have a difference in pressures, between the top of the aerofoil section and the bottom, and their mean points of action are not co-incidental, then you will have a twisting moment about the aerodynamic center. This is more marked with a cambered aerofoil with changing alpha.
If you have large wing tip vortices (low aspect ratio) then you will have more induced downwash at the tips, and consequently a reduced local alpha.
If you have reduced the alpha at one section (the tip) and increased the alpha at another (the root) to provide the total lift required, then there must be different pressure patterns over the tip section and the root section.
Different pressure patterns, different twisting moments, and therefore a torsion stress applied to the wing. Granted, it is not as marked or powerful, as the twisting moment found with a swept wing when it flexes in flight, but it exists.
Just ask the designers that use “wing warping” for lateral control!