"Even after the West began to loosen restrictions on research, and Gorbachev initiated a so-called policy of "glasnost" the gap between the Soviet Union and the West accelerated, because the base of any scientific, intellectual progress had been effectively destroyed by five+ decades of Stalinism."
In addition, as Golitsyn (high-ranking KGB defector, 1961) has explained in great detail, Stalinism was completely dead by 1957---in no way did it last 50 years. Having completely terminated Stalinism, however, the international Communist movement (in a series of meetings in Moscow in in 1957 through 1960) decided to fake its continuation---for the benefit of the West.
One key aspect of Stalinism was Stalin's idea that Russia had to completely dominate all the Communist parties of the world. This is led to the break with China. This break, however, was completely patched up in the 1957 to 1960 meetings. However, the two countries decided to continue their dispute on a fake level to suck in the U. S.---which worked, according to Golitsyn---when Nixon went to China around 1970 or so.
By opposing Nixon's move, Golitsyn undermined his own credibility in the US government and became effectively exiled from the US intelligence community.
The byproducts of Stalinism.
The purges and witch-hunts conducted by Andropov as head of the KGB, and the endless expansionism embodied by the Brezhnev Doctrine, were expressions of Stalinism, even if it went by a different name.
The refusal to abide by the protocols of the Helsinki Accords, persecuting political dissidents and/or refuseniks like Natan Sharansky and Andrei Sakharov, artistic/literary giants like Aleksandr Solzhenitsyn, Nureyev, Mikhail Baryshnikov, etc., these were all manifestations of a condition known as Leninsim/Stalinism, which the Soviet Union never completely abandoned.