What is the purpose of carrying a flight ticket receipt on paper? [closed]

I just booked a flight ticket on my next trip via DeNA travel, a Japan-based travel agency. In a confirmation email, the following note is written:

In some countries, you might get asked to submit an airline ticket receipt in a printed format, not on the screen of your smartphone or tablet. In order to get through the immigration smoothly, please print and carry it during your travel.

These countries include Philippines, India, Indonesia, Vietnam, Bangladesh, Iran, and some regions in China, etc...

However, I don't think most people carry it in this highly technologically advanced age. Well, you might like to carry it in case your smartphone's battery run out, but most people don't, I assume.

So what is the purpose that some countries like to see your ticket receipt in a printed format, which doesn't function at all to avoid a potential fraud? Would you get denied to the entry without it?