This is a very similar arrangement to Iran's "democracy" where the democracy runs but is checked by a figure whose "true" attachment is to God (or for non-believers at least to some kind of objective morality).
If you look from an average Iranian perspective, Ayatollah Khamenei is not just the leader of the country, he is also a venerable religious figure, an ascetic and someone who ostensibly cares little for worldly pleasures. If anyone were to have "guardianship" or veto power over a democracy, wouldn't he be a good guy to have it, from that perspective?
It's a lot of the same arguments you see for Trump. He doesn't need the money. He's not beholden to special interests because he's not a career politician, etc. Etc.
Just a different perspective. Many here allege torture and harsh imprisonment but these aren't inherent features of the system mentioned. They are things which could be fixed within the system as well. The same is true for American police brutality, for example.
It's also impossible to achieve, though, which makes it a bit moot. No single person is guaranteed to stay free of corruption, especially when granted tremendous, unchecked power. Creating a system that relies on this not happening is not a good idea. It's just too huge a gamble.
Also, comparing Ayatollah Khamenei, a formerly elected politician who controls around $100 billion of quasi-private wealth, to a council of ascetic monks, is a bit of a stretch.
And while we're talking about him, the "Supreme Leader" serves a lifetime term. They personally appoint the heads of the military, the government, and the judiciary. They directly choose the ministers of Defense, Intelligence and Foreign Affairs, and Science. Their successor is selected by a body appointed directly by them. The same person has held the position since 1989.
That's a fairly pure dictatorship, but agreeing with that statement might cause an Iranian to run afoul of Iran's Les Majeste laws, and Iranians are routinely punished for questioning or insulting the Supreme Leader.