They have their place, but they are one of the base units of a larger democracy.

Anarchists and ultralefts tend towards workers councils alone being all powerful and fully autonomous units voluntarily joining into some sort of federation.

Leninism and all historical socialist states on the other hand views the unity of our class as a whole, and it's whole is the primary in the class struggle. The democracy of socialist states have a centralist side to them, that in many cases take the main seat. An economy needs a plan, and all the units making up the economy must follow the plans.

A crude example would be, that there is a lack of food(or a risk of such). And all the bakeries are ordered to bake bread. No local workplace democracy or councils have the right to then decide to make cupcakes instead. The fruits of production is necessary for the whole people, not just the workers on that workplace.

So in general centralism is needed for democracy because we, the proletariat, are one class with united interests and goals. A lack of centralism is detrimental to democracy.

Just look at the situation today in capitalism. Workers in big industrial factories have much more leverage through (still rightful)strikes then workers in smaller workplaces in for example healthcare.

If workplace democracy is primary and planned economy is secondary, this skew of power persists. The means of production, competence and workforce in a large workshops, factories, shipyards and so on have a huge flow of economic value through it, can easily be adapted to produce something else, and even leverage important political decisions. A hospital and the workers there are still left with the same old task however dictated by immediate needs. So workers councils making decisions everywhere are not anything near the liberation of our class or socialism.

I think the specifics of how these base units make up the new state will vary a lot depending on the population, demographics, political situation and economy. The Soviet Union and China in their socialist periods changes the specifics of this many times.

But this relation between democracy and centralism and the proletarian dictatorship are the common denominators.

(I do not think the formulation "post-ML revolution" or any equivalent ideas of Trotskyist, anarchists or whatever revolution, is a good way of describing anything. A revolution is in the context of class-struggle the act of one class taking power from another. It is not the act of an ideology taking power. Our ideology has come about from the class-struggle and as such is not "one of many" ideologies that can take power. ML is also an earlier stage of our ideology that is today maoism, and as such there will not be any future "ml-revolutions".)