Credits, I'm sorry to see that the campaign isn't resonating with you as an experienced player, but when I was a new player, the campaign was well-paced to help me learn how different structures worked in different contexts so that I could develop strong solving intuition.
To my knowledge, most of the campaign levels were made specifically for the campaign, and furthermore, many of the authors of today either weren't active back then (like me) or weren't involved in campaign creation, hence why the author diversity is low. If you want more author diversity, check out the Ranked levels!
