It is efficient, even if it doesn't seem so. That's the whole thing about open source
You don't have to reinvent the wheel, you check how the other guys did it, do something the way you like, with the interface you like and add a feature or two. If it's cool the others can copy it instead of figuring it out again, and bother with other new features. And the user has choice to select what he likes best.

Look at DE's all of them have fanatics, all of them have advantages and disadvantages but all of them share the cool features. That is freedom.