You use something like lodash from the start so you know out of the gate you're getting something modular, consistent, feature rich, that also happens to perform well. Using a library like lodash gives wiggle room between you and the language. This wiggle room allows for increased consistency, added features, and performance improvements. For example ES6 introduces changes in `Object.keys` to support string values. Lodash standardizes the behavior so it's consistent across es3, es5, and es6 environments.