Come on guys n gals
Think it through. It's there as a standard SOP for many companies to ensure you have enough time to be stable at the threshold.
Just think how much time you'd have before impact if it was a 1000' rad alt going into EGNM, Leeds Bradford. For a UK airport it's at the exotic elevation of 700 odd feet amsl. Just prior to the threshold of runway 32 you have quite a steep escarpment. Not as steep as the other end I grant you, but very close to the threshold. Certainly not the 3 and a bit nm that 1000' baro gives you. Similar tale at runway 09 for EGJJ, Jersey with 300 foot of cliff just before the threshold lights.
Our company manuals infact define the stable approach criteria as being 1000 feet above the threshold elevation. Your steam driven barometric altimeter is the one to use (not forgetting to make corrections for ISA deviations in cold weather etc etc etc etc etc before the true techies get their piece in
)
In fact for lazy pragmatists you could replace it with a dme distance (say 3 and a bit) instead of a height. It's all about having enough distance, hence time, to sort out any minor deviations from your required flightpath.