In democratic systems disappointing leaders are replaced, often with their opposites. Errors are thereby corrected, typically over-corrected, and so the system zigzags forward, never attaining perfection because the process is too coarse and anyway the goalposts move as the world changes.
By contrast, without elections but with an ideology frozen in a bygone age the system slides towards its extinction through its failures, irrelevance, desertions or even explosive destruction.
This EU Won't Work 