An illustrator, or an animator, has to deal with the time spent filling up the page with all the figures of the crowd. A movie director needs to worry about the budget, with all those extras.
But artful composition can keep the story going while the crowd bustle about, or gawk at the main characters, or whatever you will. If the readers go back to pour over each and every figure, or a viewer to go through the scene on freeze-frame, that's their look-out; another reader can read through at a story's pace.
Fiction is linear. You can't present a whole, complex scene without going through things one by one.
To be sure, you can talk about the crowd as a group -- how the wedding guests filled up the hall. But to get down into the sensory details it has to be more individuated, in places. Even when expanding on it because it's an important scene, it has to be pick and choose and enliven the scene with details enough to convey the sensation. . . .