The System of the USSR was based on exploitation. The state apparatus owned factories and land, appropriated the results of the work of employees. Socialism is a libaration from exploitation. And the Soviet system was based on exploitation. That is, it was not socialism.
But how effective was the Bolshevik economic modernization of the country at the time of Lenin and Stalin? I invite everyone to pay attention to the latest scientific research.
I leave aside the question of whether capitalist modernization is good at all (personally, I tend to think of capitalist modernization as an unpleasant and dangerous process that should be replaced by a communitarian-councilist integral development of society). I want to draw attention to another issue: industrial growth and productivity growth.
According to modern studies of economists, prepared by a group of one of the leading Russian and European economists Sergei Guriev, the economic system of the USSR did not exceed the tsarist system. The Tsar's trend gave about the same results as Stalin's. On the other hand, the Bolshevik system has much more victims.
Guriev and his colleagues note that the tsarist system of economic modernization was ineffective in comparison with the development of the leading countries. Tsar Nicholai II severely restricted the establishment of joint-stock Companies, as he feared the increasing influence of foreigners, as well as Russian Jews, Germans and Poles on the domestic market. In addition, antitrust laws did not work in tsarist Russia.
However, according to modern scientific research, Stalin's industrial modernization did not exceed the ineffective Royal trend. Neither Lenin nor Stalin were effective managers in terms of economic development. In any case, they were no better than tsarist officials. But they were superior to the Royal bureaucracy in terms of the ability to retain control over society. You can read about it here:
https://scholar.princeton.edu/sites/default/files/golosov/files/cggt_revision.pdf