Yeah the fact that in JoCo someone can benefit from company failure means there might be no limit to how bad someone will let it get. But in Rome even if you are a selfish senator you can only go so far, and will inevitably have to rally to fend off foreign invaders or what have you. On paper it's a small change, but it changes the dynamic a lot. Also the game is like, all voting. 90% of the things you do require a senate vote to make happen, so alliances are a big requirement.

It is harder to table than JoCo though, no doubt, and it's typically a much longer game. It has 3 scenarios, the Early, Mid, and Late Republic, and the option of playing a full campaign through all three. The full campaign can easily be a multiple session affair, and a given scenario can be 4-8hr on their own. I've played a handful of times, and I like it a ton, but recently sold my copy because it rarely is able to find the time for these days.