Then, a cast of thousands has its difficulty too. A lot of them are basically part of the scenery and can be brushed over with brief allusions. But when the main characters interact with them, they have to keep them apart. Talking crowds can be very annoying when the POV character doesn't know everyone's name. And then there's when the POV character logically would know everyone's name, but the character is trivial and you don't want to misled the readers into thinking he's important. . . .
The writing life is full of dilemmas.