What the research says worry is for
Two accounts of the same thing, and they fit together rather than competing. One says avoidance is what keeps fear alive. The other says worry is a kind of avoidance you do with words.
What the research says
Newman MG, Llera SJ (2011). A novel theory of experiential avoidance in generalized anxiety disorder: a review and synthesis of research supporting a contrast avoidance model of worry. Clinical Psychology Review, 31(3), 371 to 382 doi
Worry keeps a person at a chronically raised level of negative feeling, so that they are never hit by a sudden emotional drop. On this account what worry is avoiding is the shift, not the bad state itself, which is why it can feel like sensible preparation while making nothing better.