but that person has just finished learning graphic designing so he has never worked for a single client! Now the challenge comes when the person creates his post here about his services and some people start asking about his past works while he just finished learning and he is trying to get his first customer here!
Do you think it would be easy for that person to be trusted if he had never worked for a client before? How would you interpret this person, would you dare to give him your work?
This applies in real world as good as on this forum and I can tell clearly that in most cases the answer is
no.
In most cases - for example translations and graphics - one can build a portfolio just translating or designing a few things, whether their are required/paid for or (rather) not. The one can see if they have talent / they can do it right. Without a portfolio I'd see them as just lazy beginners, hence my answer.
I was lucky to translate things (although most turned out to not be viable projects) in the earlier days. However, I gave that up for a while due to lack of time. When I came back I've translated a few things for free just to get back in business. One has to think and plan. One has to advertise even his skills. And even so there's no guarantee it will pay off. Then think on the chances of those who don't do anything...