Recently I have started to discover the charms of a faction sheet, which is rather more distilled. It has a list of the factions in the story and therefore excludes all the bit characters and lumps together all who want the same objective and are working together. Rather handy when I'm stumped in the outline. I look at the list and pick someone who could be doing something now. Preferably something that demonstrated bone-headed inability to understand the character I just dropped. (Dramatic irony is the great tool of a multi-POV story.)
Which inspires reflection on the aesthetics of multiple factions. One upside and downside are the same: they complicate the story. Which allows for plot twists and surprises all throughout, by having some faction interfere with or interrupt another's actions. But for the ending, you have to bring it all to a conclusion. Either the factions get whittled down to two -- which can be either through annihilation or assimilation into each other -- or the climax must be long and elaborately orchestrated to get them all through it in a satisfactory manner. There's a reason you usually have a primary protagonist and a primary antagonist.
It can be a good way to introduce moral ambiguity too. Evil though the Emperor is, compared to The Hero, there is goodness in the way he's keeping down the robber barons. It doesn't have to, though; The Lord of the Rings has plenty of factions, but you can tell which ones are right and which wrong; even Boromir, when he forms his own faction, has clearly gone wrong and only comes back by sacrificing his wish for his objective. OTOH, it does have the other moral aspect, that what the Good Guys want is not all the same. Indeed, it's not all compatible. The elves leave at the end because in winning, they lost their ability to stay as they would have wished.
It can also make the hero more of an underdog. Multiple forces against him are more powerful than one. Indeed, he can be caught in the middle of the fray and suffer horribly when they didn't even intend to target him. And if the forces of righteousness and light are also divided, they are less likely to help him. Always useful for sympathy.