How well this works depends a lot on the ecosystem. When working with Node.js or JavaScript in the browser, there's often a huge number of modules available. B

How well this works depends a lot on the ecosystem. When working with Node.js or JavaScript in the browser, there's often a huge number of modules available. But even though there may be six different modules trying to solve the same problem, every one of those modules may be incomplete. When working with Ruby on Rails, I find that regular Ruby gems are pretty safe. There's often one or two popular, well-maintained solutions to a common problem, and I'd be fool to reinvent the wheel. However, gems which extend Rails itself can be more problematic, and they often break during major Rails upgrades. Rust crates have a few nice properties: The Rust language itself has near-flawless backwards compatibility, Rust crates are immutable once published, and almost everybody uses semver. Oh, and cargo is great at managing dependencies. What this means is that it's often worth depending on very small libraries. Sure, maybe it's only 30 lines of code, but it's the right 30 lines, thanks to a process of refinement and to PRs from several people. So the exact trade-offs here vary considerably, depending on the details of a specific ecosystem and its tools. I do agree that for browser-based stuff—especially if you're targeting evergreen browsers—that it's often better to write a few lines of code yourself than to add a badly-maintained dependency.