Why was All That cancelled in 2005?

I've heard that the main or official reason for All That being taken off the air the first time (after Season 6) because of crew disputes and the general desire of wanting to move on. But the first revival only lasted four seasons (2002-2005). Since All That is in essence "SNL or kids", one would automatically assume that it was one of those shows that could go on perpetuity. Therefore, if one of the kids gets "too old" (I recall that being Lisa Foiles' argument for why it was time for All That to end back in 2005) then you could just replace them and keep moving on. I remember Brian Robbins, who co-created All That and is now the head of Nickelodeon saying that All That should've never gone off the air.