I think part of the issue is that it's just so easy to get a package included in "the" central registry, and for many programming adepts that's like a badge of honor. So you get many tiny libraries, and many turn into balls of mud. Then they learn about reuse and happily pull in all dependencies they can think of.
In Rust there seems to be a tendency to keep stuff out of the standard library, so everyone depends on their favorite solutions to everyday problems, which depends on their favorites and so on.
But it is a problem, because somewhere along the line one of those indirect dependencies is going to start conflicting with something else in the graph; the bigger the graph, the more conflicts.
And finally risk, because if a major indirect dependency goes belly up, that may well cause serious problems for your direct dependencies, which then makes it your problem. Also directly related to graph size.