Each does one thing well. Imagine Boost, but with every feature available for cherry-picking separately. Because there's almost no friction to add a new depend

Each does one thing well. Imagine Boost, but with every feature available for cherry-picking separately. Because there's almost no friction to add a new dependency, it's often easier to add one simple thing than roll your own. Note that nobody uses 1700 dependencies directly. Your project might use 5 deps for the 5 things it needs, but each of these libraries will use a few libraries for smaller pieces of functionality their library is composed of, and so on.