The name "fracton" was coined by Vijay, Haah, and Fu (https://arxiv.org/pdf/1505.02576.pdf) precisely because of the phenomenon you have described: individual fractons are immobile, but composites of multiple fractons may not be.

Composites of these fundamental excitations, however, are topological excitations that are free to move within sub-manifolds of the d-dimensional lattice. We term these fundamental excitations that behave as fractions of mobile particles, “fractons.”

The name "fracton" was coined by Vijay, Haah, and Fu (https://arxiv.org/abs/1505.02576) precisely because of the phenomenon you have described: individual fractons are immobile, but composites of multiple fractons may not be.

Composites of these fundamental excitations, however, are topological excitations that are free to move within sub-manifolds of the d-dimensional lattice. We term these fundamental excitations that behave as fractions of mobile particles, “fractons.”