Lots of other countries don't impose a limit in this many terms the prime minister of the head of state can be reelected... And some have a higher democracy index than the US, where such a limit is in place.
Those places also have pluralism values and free and fair elections. China is a one-party state.
It's a slippery slope.
The people of Venezuela voted to remove constitutional safeguards that saw populist Chavez stand as presidential candidate indefinitely.
Bolivia rejected a similar referendum but Morales has said he'll run again regardless - based on a court decision that throws the constitution out the window.
Not all of them. I'm just noting the lack of correlation between limit of mandates and democracy index.