The audio waveform, be it pressure or voltage fluctuations, consist only of varying frequences. Smaller details = higher frequences. As there is a limit of what we can hear, there is no point in recording (and trying to reproduce, which is another matter) those frequences. There is nothing else to this, no hidden detail or such, it is just waves.
Sample rate determines the frequency range (detail), bit depth the dynamic range. Very simple to understand.
Aural capabilities of us humans have been studied for hundreds of years and the upper limit has been fixed to around 20kHz, only now, that cheap recorders capable of more are available, people start to hear things. Is it a scientific fact or just a rationalization for new toys? I vote for the later. These are hard times for hi-fi tweaking, recording systems and media are almost perfect, cannot tune turntables and cartritges anymore, now it is to braiding silver cables... (when loudspeakers and room acoustics are the weak point of amost every system, I guess soldering crossovers and glueing boxes & acoustic treatments is not sexy enough).
Still, using 96 kHz does no absolutelly harm. Just the reasons should be rational.