I guess it's simply a different approach, but I'd rather not waste time re-implementing the wheel when I could be making software that will help somebody fulfill a concrete need.
Most people have never created the best-in-the-world implementation of anything. The math just doesn't work that way. Only one can be the best. We need to stop turning such unobtainable things into goals.
I'm not saying this is a bad thing. Progress always makes certain endeavors obsolete over time. You don't see job postings for telegraph operators any more because it's no longer useful. But if a person enjoys one of those endeavors for its own sake, it's bittersweet to see it relegated to a hobby.
I think there will always be a frontier where that is the case in software—there will always be hackers building open source projects that push some boundary, fostering their own community, and potentially changing broader paradigms—but that more and more, we're seeing a neater boundary between research (Universities, labs, projects that are essentially R&D teams at big companies) and engineering.