Of course they are invalid and that is just the point. By simply rotating without regard to how the aircraft responds, you are asking it to do something it simply cannot do. By gradually rotating, you will discover that it isn't ready to fly and can keep the nose down until you get enough speed. The Spanair pilots pulled the nose up too far for the actual condition of the flaps/slats. It's no surprise that it didn't fly but if they had eased the nose up and got no correct response, they might have been able to finesse it.
If you do this technique... then fine.. but at many airfields you will be off the end of the runway
All airliners I have flown are clear - it is a 3 degree/s rotate to a determined Pitch Attitude. There is no scope for allowance as to whether you forgot the Flaps / the 10T of cargo / the 15K tailwind.
In addition, and as may have happened here, the aircraft even with the wrong performance / configuration will "takeoff" into ground effect - the problems are thereafter.
NoD