Stages...why multiples?

[Noplasticrobots]

I feel pretty dumb asking this, as it should have been asked my first day here. 

I can usually identify the various stages in a circuit, but I was reading over the Whisker Biscuit at ROG, it mentions that it uses the Bazz Fuss as a clipping stage. I clearly see the BF in the circuit (MPSA13). My question then, is what are the other stages doing? If the BF is clipping, then the first one must amplify the signal (I'm assuming here...) but what does the last one do?

Why the need for multiple stages in a circuit? 

[DuncanM]

Gain makeup for the losses due to the tone circuit and output buffer to prevent the tone circuit from being affected by the input impedance of the following pedal/amp....?

[Noplasticrobots]

Ah ok, so if the tone stack sucks volume, you need to reamplify the signal? Makes sense.

[DuncanM]

I can't do a rigorous analysis but I'd suspect you'd lose about 10dB due to the tone network (with the wiper in the mid position).

The tone control also needs a high input impedance stage following it - otherwise it could behave oddly depending on what it was driving into...
Output buffers = good !!!   

[WGTP]

Some distortions have multiple clipping stages of different design.   

[Sir H C]

Stages usually refers to each active device in the circuit.  More gain requires more stages.  Eq often requires a gain device (before and/or after).  Just a way to separate out the circuit when you talk about it.

[petemoore]

Some distortions have multiple clipping stages of different design.   
  That's straight out of "The Distortion Sage's" cookbook.
  Working with the available ingredients, often your own recipe [it might take 10 times to get it right the first time] is a superb choice.