Yes, because some image transformations which involve change of the intensity values of the original image, such as contrast enhancement, randomGamma etc. need to be only applied to the image.
Applying intensity based transformations to the mask does not make sense since the mask is composed of discrete values 0,1,2 etc. and it makes no sense to apply intensity values to mask as it will destroy the mask values.
Wheres, spatial transformations such as flipping the image, or rotating the image should be applied to the mask as well, since the orientation of the image is changed which changes the orientation of the corresponding mask also.
Is this clear?