Don't we need a conjunction between two clauses?

Question

Isn't a conjunction such as as needed bewteen the two bolded clauses? Or, if it is just okay, I want to know why.

The desire for fame has its roots in the experience of neglect, in injury. No one would want to be famous who hadn’t also, somewhere in the past, been made to feel extremely insignificant. We sense the need for a great deal of admiring attention when we have been painfully exposed to earlier deprivation. Perhaps one’s parents were hard to impress. They never noticed one much, they were so busy on other things, focusing on other famous people, unable to have or express kind feelings, or just working too hard. There were no bedtime stories and one’s school reports weren’t the subject of praise and admiration. That’s why one dreams that one day the world will pay attention. When we’re famous, our parents will have to admire us too (which throws up an insight into one of the great signs of good parenting: that your child has no desire to be famous).

https://www.theschooloflife.com/thebookoflife/your-desire-to-be-famous-and-the-problems-it-will-bring-you/

Answer 1

This is a comma splice. It is often considered a flaw in written English (though a fairly common one, so it can't be called a grammatical mistake.

The usual way this could be punctuated is to use a semicolon to indicate two sentences with closely related meaning.

They never noticed one much; they were so busy on other things, focusing on other famous people, unable to have or express kind feelings, or just working too hard.