I staunchly believe that the 20s are a time for lifestyle exploration. No one should marry in their 20s. In the 1950s, people married in their 20s because of strict societal prohibitions against lifestyle and sexual exploration. The 1950s were a very conservative time where there was only one legitimate lifestyle for young people- so-called wedded bliss. This was rife especially in small towns.
However, in big cities and bohemian enclaves, young people in their 20s practiced a more liberal lifestyle. They did not marry at that age but experimented with different and sexual lifestyles. In such environments, early marriage was frowned upon as being unhip and traditional. However, such young people were in the minority in the 1950s.
To reiterate, the 20s are a time to explore life and career. The 20s are not a time to get married. The 20s are for living it up as you have never done before. When a person is in their 20s, (hopefully) they are on their own and finding themselves. Be alone for a couple of years to travel and act wild before marrying and settling down.
I believe in living life first and then get married. The right age to get married is in the mid-30s after life is experienced to the full. I might want to add that in the 1950s, those who have married young, were divorcing, acting middle aged crazy, and having their second youth in the 1970s. At least, this present generation is exploring every relationship and life option and when they do settle down, they have sown their wild oats and have no regrets like the 1950s generation did by marrying young.