Narrative people vs reality people maps quite well to the left/right split.
Gorbachev probably did assign blame to Chernobyl. The USSR collapsed not due to internal revolution but because the people at the very top of the system became so demoralized they basically gave up on it. Key people just stopped fighting to defend the system, and the event that demoralized them was a bit different for each.
If you look at the career trajectory of Yeltsin, who never gets enough credit for the ending of the USSR, then it's a very clear case of someone at the top levels of the Soviet system suddenly realizing just how far ahead the US was in its provision of consumer surplus. The USSR was very effective at censoring information, including from people very high up the ladder. He visited a Randalls supermarket as part of a diplomatic mission to NASA and after realizing it wasn't staged or fake, it changed him forever. He became an outspoken critic of the system from the inside, which destabilized the regime. He was exiled from power and the pressure nearly killed him as part of this, but the other Soviets never did put a bullet in his head in the way they might have done in an earlier era.
Why not? Well, perhaps because the experience of dealing with Chernobyl had sapped their confidence so much. It's easy to overlook what an absolutely massive drain on the USSR's resources and time of senior party officials it was. And because everyone knew, and everyone knew everyone knew, it dealt a huge blow to their own ability to shape the view of the Soviet system. They suddenly had to divert vast resources and years of time to cleaning up a huge disaster of their own making. Undoubtably this demoralized Gorbachev significantly, and many others.