How one confused pilot killed over 200 people..

[onelapduster]

I am a little confused as to the why the aircraft has controls which can be operated seperately? I am used to controls being joined together so either pilot can feel what the other is doing. Why is this aircraft designed like this?
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And is it just me, but why did neither initiate an emergency checklist? I cant believe they didnt verbally recognize the stall warning. Crazy!