There has been an exodus of Fortune 500 companies to other parts of the country from Los Angeles over the past 20 years — among them, Occidental Petroleum, which moved to Houston in 2014 — and with it the loss of business leaders who in other cities fill key civic roles. There were three Fortune 500 companies here in 2017, compared with seven in the City of Los Angeles in 1987. Many Hollywood executives and actors have homes in other parts of the country, and with some notable exceptions, have not played a major role in civic life here.

The region has become increasingly economically and ethnically diverse, a challenge for any political or civic leader looking to unify a community. And this is a relatively young city, filled with recent arrivals who do not have the history of the kind of old-line families who have defined civic foundations in established cities like Boston and Philadelphia.

The overlapping maze of governments works against the emergence of a single powerful political leader, such as an Edward I. Koch, the former mayor of New York City. The mayor here has little control over the school board or the health system.

Unlike New York, which has two feisty daily tabloids and a 24-hours news station devoted only to New York news, The Los Angeles Times has stood increasingly alone as other news organizations have gone out of business, such as The Los Angeles Herald Examiner, which closed in 1989. That has meant the absence of different voices and the kind of competition that can ensure a live civic debate, particularly since Los Angeles does not have the prodding that comes with an aggressive tabloid culture.

Marylouise Oates, who was an influential society columnist for The Times in the 1980s, writing closely followed columns that covered every aspect of life here — politics, Hollywood, culture, along with events in the Jewish, Latino and African-American community — said she was distressed that there were few journalistic voices in the community today.

“This city is so silo-ized,” Ms. Oates said. “I covered everything. At the time it was all one city. Otis Chandler made that possible. He decided it was a good thing to do.”

Antonio R. Villaraigosa, a former two-term mayor, said the lack of these kinds of forces was a constant obstacle to accomplishing anything ambitious when he was in City Hall.