Social democracies rely on their tax base to provide public facilities and to regulate corporations. Regulations decrease corporate profits, also decreasing the available tax base with which to regulate them.
Regulations do not always decrease profits. By ensuring safety, compensating for corporate shortsightedness, preventing negative externalities, capturing positive externalities, etc., well-chosen regulations can increase profits.
This implicitly assumes that there would be no need for regulatory organizations within a socialist state. Since most governments have ethics boards, to prevent corruption, this will most likely need to continue.
This is irrelevant. The fundamental contradiction is that funding social services for, and redistributing wealth to the working class, is contingent on the continued well-being of the capitalist class. The revenue of a socialist state does not depend on the welfare of the capitalist class.
What else would you propose? Money requires the existence of capital and private property, and gift economies are absurdly impractical for national accounting systems. It's what was originally proposed by Marx.
People could give their personal preferences in term of consumptions, works, and use of public properties. Then we use these data to allocate each of these things, in a way that maximize the material well-being of everyone. (it is just a general principle, there is a lot to say about it)
Money doesn’t require private property, you could use money to exchange right to use the public properties, and to buy services. Private property rapidly produces a monetary system, but the reciprocal is false.
In a gift economy, people would fear scarcity, and then want to accumulate goods. (hiding them). Also there would be a incentive to not work, because some would think others will not, and feel abused. (what is a vicious circle).
This is a bad idea for a few reasons: 1. Why would I save or invest with something like this? I would spend all my earnings if I couldn't gather capital in order to get more out of my work. 2. How would you determine the value of businesses exchanging with each other if they have to destroy revenue?
First of all, all economic activity is coordinated through central planning, with "projects" taking the place of individual capitalist enterprises acting independently, and there is no private ownership. We're talking about socialism, not capitalism. Could you clarify on 1?
I would have no way of predicting how beneficial my enterprise might be, since distribution is only measured by output and not the cost of doing doing business with others. No person or group would try to be more efficient, unless they could have unrestricted (despotic) access to (human) resources.
I'm afraid I can't give you a summary in less than 250 characters, but page 114-119 in Chapter 9, "Information: social problems" of Towards A New Socialism, should have what you're looking for. There's a scribd of the book in the source.
Few people in fact prefer socialism to social democracy, as evidenced by the number of supporters of each. Using these revealed preferences as the standard of "preferable", the original claim would be rejected.
This concept doesn't address the mechanism by which GDP is evaluated. It is true that rate of financial capital will outpace the value of the labor process as a return on investment is expected. However, this doesn't expect competing currency, or new markets creating demand for new skilled labor.