Those are only the known Westerlanders; i.e, the ones who are plot relevant, so they need to be given names and whatnot. There are no doubt others who are less important hangers-on among the knights and lords who travel in the royal entourage.
However, you’re leaving out some important elements of patronage:
Robert’s mouth gave a bitter twist. “Not well, in truth,” he admitted. “I think losing Jon has driven the woman mad, Ned. She has taken the boy back to the Eyrie. Against my wishes. I had hoped to foster him with Tywin Lannister at Casterly Rock. Jon had no brothers, no other sons. Was I supposed to leave him to be raised by women?”
“Kingslayer,” Ned said. The rumors were true, then. He rode on dangerous ground now, he knew. “An able and courageous man, no doubt,” he said carefully, “but his father is Warden of the West, Robert. In time Ser Jaime will succeed to that honor. No one man should hold both East and West.” He left unsaid his real concern; that the appointment would put half the armies of the realm into the hands of Lannisters.
And that’s what Cersei does when Robert’s still alive and her influence is somewhat contained. The critical moment is what happens when Robert dies and for the first time Cersei can do what she wants:
“In the place of the traitor Eddard Stark, it is the wish of His Grace that Tywin Lannister, Lord of Casterly Rock and Warden of the West, take up the office of Hand of the King, to speak with his voice, lead his armies against his enemies, and carry out his royal will. So the king has decreed. The small council consents.
"In the place of the traitor Stannis Baratheon, it is the wish of His Grace that his lady mother, the Queen Regent Cersei Lannister, who has ever been his staunchest support, be seated upon his small council, that she may help him rule wisely and with justice. So the king has decreed. The small council consents.”
“It is also the wish of His Grace that his loyal servant, Janos Slynt, Commander of the City Watch of King’s Landing, be at once raised to the rank of lord and granted the ancient seat of Harrenhal with all its attendant lands and incomes, and that his sons and grandsons shall hold these honors after him until the end of time. It is moreover his command that Lord Slynt be seated immediately upon his small council, to assist in the governance of the realm. So the king has decreed. The small council consents.”
“Your time is done,” Cersei Lannister announced. “Joffrey requires men around him who are young and strong. The council has determined that Ser Jaime Lannister will take your place as the Lord Commander of Sworn Brothers of the White Swords.”
The problem is that Cersei is bad at sharing her toys.