All systems of government are flawed, because human beings are inherently selfish. That selfishness has served us well through the history of our species, and the many ancestor species that predated humans, by ensuring that when resources were scarce, the strongest and smartest survived.
It means that it's impossible to have a form of government that completely conforms to our ideas of "fairness" or "justice", but that doesn't mean we shouldn't strive to overcome our selfishness for the common good of course.
I believe democracy, even in it's current flawed state, does introduce a measure of accountability. In that sense, it is the least shitty option for deciding who gets the power in our society.
That's an understandable view, but it's a bit reductive. People are complex. They do things for a number of reasons. Our society is configured to have plenty of reasons to make you believe everyone is just selfish, but altruism and mutual aid are as much a part of human life as self interest. If it weren't, we'd have nonstop bedlam all the time. We're very different from the rest of the animal kingdom in that sense.
It's worth considering what social and historical forces make selfishness seem like the norm. A lot of times it's just that our personal experiences confirm this to be reality because of how we were raised, runs of bad luck in an unfair system, or personal and professional networks that reward self interested behavior.
What I tend to think is useful when thinking through politics and the usefulness of democratically electing officials is that there are a variety of material and other interests that have to be satisfied by the custodians of power. They can certainly turn it into their own personal self-enrichment project, but we can also, as you said, hold them accountable every day they're in office up to and including the next time they have to beg us for our vote. There are a lot of mechanisms for this that people are often too complacent to use and even that complacency is a function of thinking they're on their own in an every man for themselves society. Making us believe that's how things are is the number one way power maintains and reproduces itself. Collectively, we can press for our shared interests in common, and we can democratically exercise our shared will. It's just incredibly hard work. But look, we do it on this forum, for example, every day.
@Splinty could be making millions off of this place making us buy blue names and selling our data to corporations, but instead he and the rest of the ownership team are beholden to their beloved users.