I see. Thank you.
The Sims 2 personalities helped sims to build some skills faster. For example: Serious sims build Logic skill faster while Playful sims build Creativity skill faster. Culinary career requires both Logic and Creativity skills, thus this guide marks it as "Serious or Playful".
In a sense, this has made past The Sims 2.
The Sims 3 had a lot of traits that helped in skill building. There even was traits that helped with the career performance. And then there was Supernatural Skeptic, which helped with Business, Political, Law Enforcement, and Journalism careers.
The Sims 4 traits are more helping your sims get into the right emotion to build certain skills faster. There are few new ones that help with skill building too, like Nosy sims build Photography and Writing skills faster (making them good Writers for example).
So, in a sense it's just some small feature in a guide that you can easily find trait alternatives for in the future games.