Edit: to be clear I am not endorsing either system, just describing them as accurately as possible.
Many of the worst actions of repressive regimes have usually been motivated by emotions, not expediency. As more people get involved, the chance of any single personal obsession resulting in crass harm to, for example, a certain group of citizen is lowered.
Competition for power among people and/or these institutions also results in a sort of crude "checks and balances". There are too many people with considerable power that it becomes impossible for all of them to move billions to Switzerland, and if only a few do so, they risk being taken down by others who get jealous.
Of course, as China shows, this is still far below the standards set by real rule of law. But compare China with the half-bit dictators (Qaddafi, Barack Hussein) and it's hard to deny that it's not quite that bad.
Comrade Stalin didn't become Vozjd because the Bolshevik party wanted to instill an all-powerful dictator. Like Xi, he decisively won a power struggle in a government which was originally composed of a number of powerful committees.
The revolution had ~30 fathers - yet, 13 years after Lenin's death, all but one of them - Stalin - were dead, in a GULAG, or in exile (And soon to be dead).
The only way to protect against despotism is to have relatively frequent turnover in government. If US presidents and congresscritters were elected for 20 year terms, the US would have long ago become a dictatorship.
The police will continue to repress, the press committees will continue to censor...