Citadel was a big city, with a population of millions of people living here, considering Upper Ring and Lower Ring, so people must have their celebrities.
People were inclined to follow someone, to give their likes to someone. Sure, the Citadel made movies, music, and various shows, it was an important part of the economy and a moral component for ordinary people.
But... given the world they lived in, no celebrity, idol or musician could compare to the popularity and recognition the Phantoms had.
The Phantoms hardly gave interviews, they didn't do movies or commercials, and they didn't participate in public events, but... none of it made any sense.
Most of the footage of NEPs during missions was available for anyone to view, the missions department rarely hid anything.
Few ordinary people were involved, but the media helped them. They picked the most outstanding fights and spread them as much as possible to gain views.