"to praise someone or something so that other people think they are really good, or so that they have more confidence"

[hardyweineberg]

"to praise someone or something so that other people think they are really good, or so that they have more confidence"

Source:https://www.ldoceonline.com/dictionary/build-up

1) What justifies the use of a comma before "or"? The clause that comes after it is a subordinate clause, and grammar rules dictate that when this type of clause comes at the end of a sentence, a comma shouldn't be put before it.
Source: this website and several others:https://prowritingaid.com/grammar/1...ordinate-clause#:~:text=It turns out there is, %22%20and%20%22although%22)

2) So if I am using a structure like this--main clause + subordinate clause + and/or + subordinate clause--do I have to put a comma before " and" or "or"?
For example, should I put a comma before " and" and "or" in these sentences:
A) "I made a very poor and irrational decision yesterday because I was very tired and because my father did not guide me properly."

B) "He will pay for the dinner tomorrow if he comes late or if he wins a bet."

According to what I've been taught, commas should never be placed before clauses like "because my father did not guide me properly" as they cannot stand on their own. However, it seems a lot of newspapers and English writers don't follow this rule.

 

[jutfrank]

1) When the subordinate clause precedes the main clause, separate the clauses with a comma. When the subordinate clause follows the main clause, a comma isn't necessary. However, in the latter case, when you want to make a point of breaking up the clauses for reasons of clarity, use a comma to do this. The effect is that you get the reader to pause briefly, to take the information in before going on with the sentence. This is especially useful with longer sentences.

2) No, you don't have to, but it's often a good idea, for reasons I've explained above.

 

[SoothingDave]

Yes. The comma is there to assist the reader with the long sentence.