In the context of protocols for peer-to-peer open computer networks -- those in which new actors can freely enter and immediately start participating in the protocol --, without any central entity, specially without any central human mind judging things from the top --, it's common for decisions about the protocol to be thought taking in consideration all the possible ways a rogue peer can disrupt the entire network, abuse it, make the experience terrible for others. The protocol design must account for all incentives in play and how they will affect each participant, always having in mind that each participant may be acting in a purely egoistical self-interested manner, not caring at all about the health of the network (even though most participants won't be like that). So a protocol, to be successful, must have incentives aligned such that self-interested actors cannot profit by hurting others and will gain most by cooperating (whatever that means in the envisaged context), or there must be a way for other peers to detect attacks and other kinds of harm or attempted harm and neutralize these.
Since computers are very fast, protocols can be designed to be executed many times per day by peers involved, and since the internet is a very open place to which people of various natures are connected, many open-network protocols with varied goals have been tried in large scale and most of them failed and were shut down (or kept existing, but offering a bad experience and in a much more limited scope than they were expected to be). Often the failure of a protocol leads to knowledge about its shortcomings being more-or-less widespread and agreed upon, and these lead to the development of a better protocol the next time something with similar goals is tried.
Ideally democracies are supposed to be an open-entry network in the same sense as these computer networks, and although that is a noble goal, it's one full of shortcomings. Democracies are supposed to the governing protocol of States that have the power to do basically anything with the lives of millions of citizens.
One simple inference we may take from the history of computer peer-to-peer protocols is that the ones that work better are those that are simple and small in scope (Bitcoin, for example, is very simple; BitTorrent is also very simple and very limited in what it tries to do and the number of participants that get involved in each run of the protocol).
Democracies, as we said above, are the opposite of that. Besides being in a very hard position to achieve success as an open protocol, democracies also suffer from the fact that they take a long time to run, so it's hard to see where it is failing every time.
The fundamental incentives of democracy, i.e. the rules of the protocol, posed by the separation of powers and checks-and-balances are basically the same in every place and in every epoch since the XIII century, and even today most people who dedicate their lives to the subject still don't see how they're completely flawed.
The system of checks and balances was thought from the armchair of a couple of political theorists who had never done anything like that in their lives, didn't have any experience dealing with very adversarial environments like the internet -- and probably couldn't even imagine that the future users of their network were going to be creatures completely different than themselves and their fellow philosophers and aristocrats who all shared the same worldview (and how fast that future would come!).