If you're using N separate libraries, that's N times the likelihood of breaking changes that force you to migrate at inconvenient times, and O(N^2) opportunities for bugs caused by incompatibilities.
Two libraries can misbehave because they share a common dependency.
If you assume a roughly logarithmic intersection of shared dependencies that's O(N^2 log n) chances for a bug. But in some communities I'm sure even that is optimistic.
