Originally Posted by
TejanoTrackie
Because in the majority of situations it results in the most comfortable setup.
For competitive cyclists
saddle level was part of Step
#3 of 7 in a "baseline fit" for new riders on the track or road.
Why? It works for the great majority of properly fitted and conditioned riders, it's UCI legal and it's the known baseline to adjust from.
Don't like it? As always suit yourself.
-Bandera