Yes, in the question asked in the second person, the 'why don't you be' construction implies an imperative, which doesn't work in the other persons.
The implied imperative remains with the second example, though.
No, because that's in the third person. The imperative needs to address the person being spoken to.
@fizzy.bleach started
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Yes, in the question asked in the second person, the 'why don't you be' construction implies an imperative, which doesn't work in the other persons.