Is that not common knowledge? I feel like this is a well-written post with a good point but it's a familiar point. You could boil part of it down to 'all's good in moderation', so don't just keep your code clean, keep it clean and easy to read, etc.
Your common knowledge isn't necessarily everyone's common knowledge; what you perceive isn't necessarily what it is.
Every day there are many people just starting to code. There are cultural and regional differences. They might not have hit the exact spot in which this information appears.
Knowledge also disappears, fades, gets censored or destroyed, gets mixed up and remembered incorrectly. You might take something as a given and misremember it 20 years from now. You might read your own code 5 years from now and not know why something's there — something that was taken to be obvious.