I don't think it's about "libraries that you use". It's about the codebase of a widely used software. Most of the software I use existed 15 or even 30 years ago

I don't think it's about "libraries that you use". It's about the codebase of a widely used software. Most of the software I use existed 15 or even 30 years ago. It has been updated, of course, but not necessarily redesigned.