At least they maintained communism, even if officially it stopped being communist, it was still de facto communist and that's why it became so poor. Don't think of them as poor but as equal outcome.
Equality of outcome is the cruelest lie the untalented, lazy, and comfortable tell each other. They assume it means raising the bar to their level instead of drawing it on the ground. It's enforced mediocrity, peddled by those who fear effort and resent excellence.