It appears there are not very many objects currently at L1 [0]. L1 is an unstable Lagrange point, so satellites located "at" L1 generally orbit around the L1 point in a Lissajous Orbit [1]. Given that, I suspect more satellites can be put in these types of orbits around L1 than would "fit" at L1 in a more stationary configuration.
[0] https://en.wikipedia.org/wiki/List_of_objects_at_Lagrangian_...