It's because of the technique itself; because of the longer drying time oil based is used; acrylics dry so quickly (in comparison) the time needed to do what you want is very short, so results are problematic and “redoing/correcting" is not too successful because the acrylic paint is dry or very nearly so.
However remember If you want to do something don't let the "conventional wisdom" keep you from it. You never know, you may stumble on a method that becomes the latest "new best way", in the modeling world.
Then you'll be a hero and we will wonder why we doubted you.
HTH