I asked this question before, and I accepted a well explained answer. However, I am still struggling with the problem. In the meantime, I did my own research which further led to more confusion.
My problem concerns the use of commas. Others, who hold esteem positions in the usage of English Language have suggested that the commas are necessary. [shown in square brackets].
According to Sautter (1980), authorities feared that the end of the war would leave thousands of workers from the weapons industries [,] and at least half a million demobilized soldiers [,] out of work and out on the streets.
Note: I feel that the bold part together, joined by "and" is essential to the meaning of the sentence. Putting "and at least half a million demobilized soldiers" within a pair of commas makes it nonessential. But it is not nonessential information and without this, although the sentence would make sense, the meaning of the sentence would be significantly different. "Essential clauses are necessary to identify the person or thing that is being described. They are essential to understanding the sentence. They restrict the meaning to that specific person/thing." According to this, the part about soldiers limits the meaning of my sentence, and it is thus essential.
Also, according to this: https://owl.purdue.edu/owl/general_writing/punctuation/commas/extended_rules_for_commas.html Point number 14 says Don't put a comma between the two nouns, noun phrases, or noun clauses in a compound subject or compound object.
NOTE: Link to the first question for complete context. Comma usage and placement