When you are one member of a house of 100, you have one vote in 100. 1/100
If the house splits on party lines, and you are one member of 55, you have control with one vote in 55, 1/55.
If your party splits on factional lines, and you are one vote in a faction of thirty, you have 1/30th control of the country.
This only works if you have strict party control of the house, and strict factional control of the party.
Conditions that are met in China, but are presently weakening, because at present China is moving from factional control towards one-man control. Even if China turns back into a strictly one-man dictatorship, factions continue to exist because of history/tradition/political inertia.
In contrast, American politics is presently moving towards strict party division, and strict factional control, conditions that favour the existence of factions, but moving away from a period of weak party control and weak factional control, so the caucuses that exist at present have weak factional control and a history of flexible membership.
I wish to clarify that I do not think that American politics presently has "factions" as a structural part of politics, as some parties in other countries do, and I do not think that there is presently strict party discipline, as exists in some other countries. I think that it is observable that American party discipline is stricter than it was 20 years ago, and strict party control and factional control may exist some time in the future.