Chord symbols are meant to primarily tell us what the sound should be a given place, and so a Jazz musician would have different interpretations of a (for example) C7#11 compared to a C7b5. Yes notes can be and often are omitted in voicings but remember, first, that chords are built from the root up through its extensions. This means that the basic triad sound of a Bbmaj7#11 versus a Bbmaj7b5 is already different, as the basic triad of a Bbmaj7#11 chord is Bb-D-F, and of a Bbmaj7b5 is Bb-D-Fb, leaving out a stable sounding fifth in the chord entirely (if you sit down and play these on piano, you'll also notice that maj7b5 chords sound very dark in comparison to maj7#11 chords; the natural fifth does indeed make a difference). Now they both might imply a Lydian-ish sound, but in the second chord (Bbmaj7b5) the flatted fifth has entirely displaced the natural fifth also meaning that if I play a natural fifth over the chord's flatted fifth, it will destroy the chord's actual quality, and will probably clash too. Conversely, playing the fifth in a Bbmaj7#11 will not destroy or alter the basic sound of the chord. As far as interpreting the chord symbols, going back to the C chords from earlier, I might interpret the chord scale of a C7#11 as C Lydian Dominant as the Lydian dominant scale has a natural fifth, a flat seven, and a sharp eleven, and over a C7b5 I might play the C whole tone scale as the whole tone scale has a flat fifth and seventh, but no natural fifth whatsoever. The Lydian dominant scale and the whole tone scale are very different sounds, so even though two chords might have "similar" constructions and similar voicings, they can imply very different overall sounds.