[Asterisk-Users] Why use 'Answer'?

[Rich Adamson]

Why is it that newcomers always feel like inserting 'Answer' is a
necessary step in their extension.conf entries?

>[voiptalk.org]
>;forwards any calls starting with an "8" thru voiptalk.org
>exten => _8.,1,Answer
>exten => _8.,3,SetCIDNum(55555555)
>exten => _8.,4,SetCIDName(My Name And Surname)
>exten => _8.,5,Dial(SIP/${EXTEN:1}@voiptalk.org,,g)
>exten => _8.,6,HangUp

I fully understand that incoming pstn calls have to be answered (in
most cases) before executing a Playback(invalid) type statement. But
there must be some examples, documentation, or somthing that is 
suggesting to newcomers that all sequences have to start with an Answer.