> programmers agree that simpler solutions...are preferred, but the disagreements start about which ones are simpler

Low ego wins.

1. Given: The quality of a codebase as a whole is greatly affected by its level of consistency + cohesiveness

2. Therefore: The best codebases are created by groups that either (1) internally have similar taste or (2) are comprised of low ego people willing to bend their will to the established conventions of the codebase.

Obviously, this comes with caveats. (Objectively bad patterns do exist.) But in general:

Low-ego → Following existing conventions → They become familiar → They seem simpler

I don't think this necessarily is accurate I've come into a lot of projects that no one understands well, but everyone continues to follow the same bad conventions that already exist which just adds to the problems. Ex: deep nesting, no early exit, deep object inheritance.. this happens because a lot of developers don't want to rock the boat, AND because they don't have the skills to unwind the complexity in a manageable amount of time without also causing serious problems.