If we look at even animals in the wild, they too have the tendency to have a specific territory and another being entering it is considered hostile. So boundaries do exist partially even in the animal kingdom. Now taking in to account the world even during ancient times, conquest and capturing of territories was common even then, man developed specific boundaries and areas which can be considered his/her own in accordance with their race or ethnicity, which gave the innate nature or feeling that they need to protect it form outsiders(just like the animal kingdom).
Thus it is hard to imagine the world without boundaries as it is human nature to do so, but as specified in the quote and in an hypothetical situation, where no boundaries existed and were created, it would have led most probably to a single governing body deciding the movement of resources, people, etc. This would have caused widespread corruption. As people need to be led, and without boundaries, as mentioned a single leading force will be formed( the governing body mentioned), which would decide everything. And with such a large area its hard to make every voice heard thus possibly ruling out a democracy, and resulting in a autocratic rule, which goes back to corruption and injustice as mentioned. Now on the positive, there would be no racism, no communal violence , and people would be able to move from one place to an other freely, thus it could inspire harmony and peace at least in a small scale and among the people in the vicinity or wherever a person decides to go, there would be no differentiation.