My definition describes how Socialism happens in practice. It is based on my lived experience of a partially Socialist society which is more liberalised now (not nearly enough). It is also informed by accounts of the generations before me who lived in a far more socialistic pattern of society and actually suffered through the atrocities.
The expansion in the material I shared is quite important. It includes collectivisation of consciousness, property ownership and redistribution of wealth which requires my definition of Socialism to happen in practice, which involves aggression, coercion and a rejection of an individual's aims in life, to live within his or her truth and the violation and rejection of his or her natural rights.
It is a social order and ideology that is ineffective, goes against basic incentives, causes suffering, stagnation, resentment, envy, corruption and conflict.
Why do I say this?
Because I see it happening right now.
Socialism requires me to reject the notion of non-agression and voluntaryism, to give up my property rights and the economic calculations I make to take care of myself and those i care about.
The source material you just shared itself accepts that there are different definitions of Socialism. I can guess that there are possibly hundreds more.
My definition is simply another one of them, based on my experience of it. I do not claim it to be canonical. You are free to reject my definition.
Your source material also claims that Socialism is not the same as statism.
My claim is that Socialism inevitably leads to statism. It always has, and always will.
Lastly, my rights and aims of life do not care about credentials or expertise. If there is something that violates them, I will reject it. Ergo, I reject Socialism.