The real problem is when you get to scale. At a company like Facebook or Google, it seems like you end up spending half your time simply looking for similar cod

The real problem is when you get to scale. At a company like Facebook or Google, it seems like you end up spending half your time simply looking for similar code that other developers wrote to solve a similar problem so that you can avoid duplication in the codebase. When you have tens of thousands of developers that becomes VERY challenging. Code duplication is one of the biggest mistakes I made as a new developer. As you became a better engineer, you learn how to simplify and extract common patterns into shared classes/libraries/components to avoid duplication. Code duplication is almost a cardinal sin due to the complexity and bugs that tend to result.