A question for Google Analytics Experts

Hello Members,

I have this one question since so long and I found nowhere else to ask about it. Many of you may know about this website named "thisiswhyimbroke". The question relates to this website.

Note: I have already read out the whole AMA from "thisiswhyimbroke" Owner which was done on Reddit a few years back.

So my question is:
The website uses UTM tracking codes [ utm_source=thisiswhyimbroke.com&utm_medium=referral ] with most of its products listing.

I do not know much about it but I know its simple tracking codes in Analytics to track the number of referrals from a given source.

NOW I want to know is what could be the actual reason to have all those thousands of tracking codes?

Could it be for the product owners to show them the actual number of traffic they got from "Thisiswhyimbroke" or there could be something I am missing?

What possible benefits of using this for a site like this? Please share your thoughts on this.

Ans is there any limit for a single G Analytics account to use UTM codes?

All thoughts are welcome. Thanks!