User blog:Jonny16/What is the meaning for Oda having Sabo killed??

Okay guys, so here is my question, when Ace died, we had a flashback of the kids history right? But what was the meaning introducing Sabo in the story and have him killed afterwards, do you guys really think Oda introduce a valuable character just to have him killed or to be able to make a twist in the story with him?

Please give me your opinion guys.