The risk is much bigger than simple lifecycle testing will account for. Upstream micro libraries could easily disappear or have bugs, leaving you spending more

The risk is much bigger than simple lifecycle testing will account for. Upstream micro libraries could easily disappear or have bugs, leaving you spending more time trying to workaround than if you had just written the darn thing yourself in the first place. Or, you suddenly have a new requirement that doesn't play well with the lib. Programmers loves dependencies because it lets them pass the buck, but each and every 3rd party module is a potential time bomb waiting to happen.