We should punish even obvious sockpuppets for slippery-slope reasons. Any sockpuppet, obvious or not, accepted by the community will be interpreted by someone as a signal that there's nothing wrong with sockpuppetry.
Also, I have a moderate to strong distaste for bizarre behaviour, such as creating obvious sockpuppets when there is no obvious reason. Absurdist fiction is not my favourite genre.
In fact from a slippery-slope/community norm point of view obvious sockpuppets are worse than non-obvious ones.
I thought it would be good to play the irrationality game again. Let's do it!