I’m not sure it’s that different. In place of a real personality, you get the country’s persona. With US foreign policy for example it matters little who leads because they are adhering to the persona. While the majority of Americans don’t want war, the US persona does. That results in the same thing (a population ruled by one idea set) just a hologram of person rather than an actual one.
Many oligarchs is better than a single oligarch. In true capitalist fashion, they are sociopathically self interested and their undermining of each other can occasionally benefit the rest of us.
And one time they almost got into a ring to fight, which was pretty funny.
Both situations are bad, but I don’t think oligarchs hinder each other that much. They compete, but in their overall control of society they are fairly unanimous, because they all share the same basic material interest to pay us as little as possible for as much work as possible and to destroy any trace of meaningful working class political power that might challenge them.
For the most part, their interests align, that's true. And it could be copium to say that many is better than one - since that's what we have.
At least if there was only one oligarch, we could have direct communication - as it is now, all the oligarchs can just kinda shrug their shoulders and mumble something in the universal language of plausible deniability.