Some things we do kind of make sense in and of themself. Some things have evolved to be the way we do it but just don’t map up to our brains cleanly at first.
What are the non-intuitive parts of our craft?
Soft skills are as critical as technical skills for a software engineer. No one works in isolation. Each person has to deal with teammates, colleagues, managers, etc. Therefore team interpersonal skills are essential too. Soft skills include things like good communication, honesty, teamwork, integrity, organization, empathy, etc.