It seems to me that academia is not a meritocracy.
A meritocracy is a system in which commercial success and political power is vested in people on the basis of talent, effort, achievement, and good ideas, rather than wealth or social class. Advancement in such a system is based on having good ideas, and writing, sharing, and practicing them.
However, the people who succeed in academia are not necessarily the ones with the best ideas or writings. Many times, they are the ones with the best social skills and likability.
For evidence, simply look at Twitter. There is a vibrant community of philosophers and academics on Twitter. They use it as a place to express their personal opinions, share their academic work, and make connections with each other. Yet, the academics with the most followers, retweets, and likes are not the ones with the best ideas or writings. They are only the ones who have developed enough clout to be "Twitter famous".
The same concept is applicable to academic institutions. Administrators and academic departments use academic citations to measure the impact or notability of a person's work. They are an important part of determining a person's fit for promotions and hiring. If I remember correctly, philosophers usually need at least twelve articles (two per year) published in peer-reviewed academic journals by the time they are judged for tenure. In order to be promoted to a higher position, such as full professor, they need to create significant work in the field, such as a book in a notable subject.
A work is usually considered significant or notable when it is cited by others, but academics who discuss more popular topics or are simply better at getting others to follow their ideas or like them (i.e., socializing), are more likely to succeed. When people like you, they are more willing to listen to what you have to say and engage with your preferred topics of discourse. Therefore, you are more likely to succeed as an academic when people like you more.
Thus, the way that academics judge younger members of their community is flawed. Some academics may have great ideas and can express them well in writing, but may be unable to socialize in a way that makes them likable. Perhaps they are harsh or they have an unpopular opinion. Maybe they are strong-willed and unwilling to accept what the way society is structured, or perhaps they are unafraid to speak up and make noise when they have disagreement. These habits and personality traits can nudge the people with hiring and recruiting power to think of the younger members as unlikable, unacceptable, and therefore not a good fit.
In other words, just because an idea is popular does not mean that it is good. Academics are also plagued by groupthink.
But then, how do you decide which ideas are the best? Obviously, that is difficult question to answer and I will not attempt to answer it here.