I both agree and disagree.
I really hate seeing stacking Doran's items. But not because it's overpowered, because it's a sell out.... they don't build into anything and if the game progresses long enough, those who just went straight for full builds will do better in the end.
However, it -does- give an advantage earlier on, usually. This means that a good team who's facing a Doran stacker (or multiple ones), will play really cautiously and continue farming, extending the laning phase by quite a bit. Which means longer games, unnecessarily so.