Well, in part because a meaningful sentence tends to be more easily remembered and also more useful than a meaningless one. So if I have a meaningful & useful sentence, I'll use it in conversation, and therefore remember it. This particular example is meaningless and, therefore, mostly useless.
Mostly of the romance languages have two genders for the countries.
Literally 'Nation' is femenine and 'Country' is masculine.
The example is clear, and it's not real... They made it like that, just to practice romanian... It shouldn't have necessarily a meaning or needs to be true or real.
Another example is in Portuguese for spanish speakers:
'The insects learn portuguese with Duolingo'.
Obviously, people make jokes about that and how Duolingo is calling 'insect' everyone.
I have learned that language didactics in general condemns useless or doubtful sentences because the readers/students never now if it is an idiomatic expression, a meaningsless sentence or an actual sentence and therefore cannot know what is expected. It is very frustrating! Compare mustard ridden ankles...