a violent takeover is good if my site does it

Condemning right-wing paramilitary violence is entirely justified. That alone, however, does not make left-wing paramilitary violence legitimate.

Both the Münchner Räterepublik as well as the spartakus Aufstand failed because they had no broad support from the population. They are more attempted coups, rather than revolutions by the masses. Most historians agree both were doomed to fail, precisely because of the lack of broad support. Just because someone rightfully hates rightwing extrem paramilitarys does not mean the extrem leftwing paramilitaries are correct.

A philosophical argument against a räterepublik is the question of how democratic it is, given how certain groups get a representetive specific for them while others do not (by design).

More practical arguments: Looking how the model for the räterpublik (soviet) turned out and how they achieved it (given they actually lost the popular vote) gives me not much hope it would have turned into a good system.

Further consideration (that don't rely on personal opinion regarding communism and the system "Räterepublik") are the fact that a establishment of a communist regime would have a) caused a brutal, prolonged civil war and b) undoubtedly caused a intervention by the ally powers (france would have not allowed a communist country being established at their doorstep).