Why Gorbachev?

Why Gorbachev?
Gorbachev is of the same age as I am. Several days ago I read a post (on a Russian forum) in which he was accused of being responsible for the disintegration of the Soviet Union. In my opinion the country disintegrated spontaneously, after the truth about dark sides of Stalinism became known. Yes, Gorbachev, the leader of the Soviet Communist Party, did contribute to the fall, by promoting the policy of “glasnost,” that is by allowing truth to be known. But reforms introduced by the President of the Soviet Union, Yeltsyn, were equally important. The same can be said about Gorbachev’s predecessor Khrushchev, about Solzhenitsyn, Shalamow and Pasternak, whose books were allowed to be published, and about authors of many other documents.
Karl Marx would say that focusing on characters of exceptional individuals, such as Lenin, Stalin and Gorbachev, is not sufficient. He would most probably try to identify mistkes made by those who managed the country’s economy, focusing on nationalization of means of production, collectivisation of agriculture, and on dealing with some national aspirations.
Ludwik Kowalski, Ludwik Kowalski
A Russian author wrote:
“Gorbachev must be put on trial! This diversionary enemy worked for western intelligence services.”
“Судить Горбачёва необходимо! Это враг, диверант который работал на западную разведку!”

What structural changes if any, or how much was made, to the oligarchs in the transitional phase between, Gorbachev-Yeltsin-Putin?
What structural changes were made to the KGB and other apparatchik to allow them to transition from peaceful co-existence(symbiosis) with the oligarchs under Communism, to peaceful co-existence(symbiosis) with them under the provisional and then current form of government?
How much of the old KGB and other apparatchik maintained their power through the transition, and how did the Oligarchy transition along with it
through these phases? How much power did they maintain? Especially through the Gorbachev-Yeltsin-Putin phase?
It’s my understanding that after some turmoil and re-adjusting, the core of the changing(adapting!), old Apparatchik(ie KGB) was able to maintain power alongside a changing/adapting oligarchy.
During the transitional phase-somehow Putin(being relatively young, possibly part of a New Guard, (a new guard with excellent foresight and adaptability.) managed to corral the apparatchik under his wing and integrate with select oligarchs to form the new government.
Old system of operation pretty much unchanged-just new name and new faces mostly. Plus other conditions concurrent with today’s global
economy and European situations.
Plus a good dash of the Glasnost and internal reforms of Democracy staying along for the ride. To a slight to moderate extent.
Again old system still intact, just brushed up and polished with a new name.