Board Thread:Legitimate Canon Questions/@comment-4467206-20161117104304/@comment-4091815-20161118205841

I've explained this elsewhere - Only their memory of the person is gone.

The person still existed, still did all those things we're talking about, but the individuals simply don't remember him being part of those events.

The Riders also take away anything that could remind anyone that someone is missing, the photos, furniture etc.

This time they seem to have bitten off more than they can chew. Since Stiles is such a major part of everyone's life, pieces of him will remain even if only in the numerous gaps in memory everyone will suffer.