Well just from my own personal research (which is not nearly as thorough as I'd like), structurally any central power structure receives little benefit from division of labor and the main driver that allows it to work and greese the wheels are corruption, which generally promotes oligopoly or monopoly.
Then you have the economic calculation problem, inability to adjust to shortages because the economy is not self-moderating, low to zero visibility (and shame) so responsible parties may not communicate to enact change rapidly or admit there's a problem until its had significant cost.
Generally speaking, there is also a lot of indoctrination, and many who grow up in those places see the only solution to failures of socialism as more socialism because it failed because there simply wasn't enough, and it is after all about the group over the whole with identity politics.
Improvement is impossible because failures can't be acknowledged or reconciled rationally.
Structurally over time its a fundamentally unstable system as people age out of positions of power, newer generations may not be properly educated (they all drink the same coolaid).
Rational pragmatic and constructive thought is kind of a requirement to improve.
There's also usually a good portion of the population used as disadvantaged labor that supports an aristocratic elite.