Why do we publish papers instead of just open source code?

This just a random thought.

I sometimes heard people claim that why researcher don’t just open source code instead of publishing their paper. They would use open source code to check which is better.

Because the main purpose of research is not the final product or near-final product. It is about expanding knowledge of science comunity or people in certain area. To serve that purpose, authors must have a report that summarize the problem they are trying to solve, their proposed idea, compare their approach with other approachs. All mentioned points need to be proved with experiments or rigorous theoretical provement.

Imagine thousands of people open their source code, how can anyone review thousands and test those thousands source? People would fall into which source code provide best visual effect.