Why do immigration offices care whether the money used as evidence is funds is borrowed?

Maybe the answer is obvious but I don't really get it, hence why I'm posting here.

I was looking thru a friend's application to immigrate to Canada and I came across a phrase repeated several times in various places. Paraphrasing, funds from a gift deed ​must be proven to be unencumbered, not loaned, etc etc. I have also had another friend's immigration application queried because the funds were said to be suspicious, probably borrowed, due to their previous account history.

These have me wondering, why do they care if the applicant borrowed money? The country is in no way liable for their debt. I feel like as long as the person meets other criteria (of these often economic streams) how they source their money and how they pay back should not be a concern. Of course if criminality is suspected then that's a different matter entirely. I'm talking about just loans.