It's autistic / adhd hyperverbosity. Rationalists are a social group of neurodiverse people and attract neurodiverse people as a result.
> adding layers of detail and nuance rather than interrogating the one or two assumptions they make at the start
This is a fundamentally neurotypical assumption. NDs have a hard time understanding the shared context of their audience, so they splay out all the detail to compensate. Earlier in their lives they tried 'just interrogating the one or two assumptions' but because they are not able to infer context nobody understands them because they are off the mark. They also enjoy diving into a huge amount of detail and exploring every nook and cranny to potentially find something new.
> adding layers of detail and nuance rather than interrogating the one or two assumptions they make at the start
This is a fundamentally neurotypical assumption. NDs have a hard time understanding the shared context of their audience, so they splay out all the detail to compensate. Earlier in their lives they tried 'just interrogating the one or two assumptions' but because they are not able to infer context nobody understands them because they are off the mark. They also enjoy diving into a huge amount of detail and exploring every nook and cranny to potentially find something new.