Military service is a quantifiable indicator, such as how many beheadings, how many prisoners, how many materials were seized, and how many cities were conquered and surrendered. Qin broke the monopoly of official positions through military service, which injected fresh blood into the upper echelons of Qin, increased the fighting spirit of soldiers and enhanced the national strength of Qin.
However, Shi Qing did not completely disappear. Shi Qing was originally a family with the same surname, or a descendant of a hero with a different surname who helped Qin Jun to farmland. Because of the glory of their ancestors, they can get high officials and high salaries, regardless of their own advantages and disadvantages. This is the so-called Shi Qing. The implementation of military posts has broken their golden rice bowls, and most people have to strive for a future for themselves with their own efforts.
But there are some exceptions.
As Qin Jun, can you treat your son and your own brother well? Can you give preferential treatment to your own brothers and cousins? What about my great-great-grandfather's brother? What about the one with the great-grandfather? Of course, you can't give discounts to everyone, because cakes are limited, and people are close and far away. Good treatment must start with intimate relationships. You can let the relatives who have been in contact for eight generations go to war, but what if they are the sons and brothers of the king of Qin? I don't think he is willing to give up.
Therefore, the rank can not be applied to everyone, so there is the title of Jun, which is flexible, the salary can be low or high, and military service is not required. As long as the king of Qin is happy, he can give titles to anyone. Of course, in order not to undermine the mainstream position of military titles, it is better to seal as few titles as possible.
Most of the monarchs are close relatives of the King of Qin, such as the four big noble and the three monarchs in the period of the King of Qin. They are my uncle Ran, my uncle Hua Yangjun, my brother Gao Gongzi Ji and my brother Jingyang Junzi Bi. There is another kind, mainly civilian counselors, because it is difficult to measure their thoughts by military exploits, so they also use the title of monarch instead of the title of marquis. For example, Wu Xinjun and Zhang Yi used Lian Heng to break the alliance, and their contribution is hard to be measured by how many enemies they killed, so they sealed the title of monarch instead of marquis.
Therefore: Hou is the culmination of the title, with the highest salary, which is obtained by military service. Your salary can be low or high, from the king.