I think the idea is like that: if you think that the murderer in a A. Christie's story is shown unrealistically, you can write it off as a literary device to create an entertaining puzzle, and not expect a serious treatise on the criminal's psychology, motives, etc.
If you need a deep(er) view of a murderer's soul, you open Crime and Punishment, also a literary work and not a piece of academic research, and find it there.
For SF in 1970s, there was no such higher tier; there was no literary futurology. Lem himself was one of the biggest figures in the field of literary futurology, framed as SF. "Hard SF", like the works of Peter Watts or Greg Egan, did not yet exist.
If you need a deep(er) view of a murderer's soul, you open Crime and Punishment, also a literary work and not a piece of academic research, and find it there.
For SF in 1970s, there was no such higher tier; there was no literary futurology. Lem himself was one of the biggest figures in the field of literary futurology, framed as SF. "Hard SF", like the works of Peter Watts or Greg Egan, did not yet exist.