Author here! My intention with "domain knowledge" point is mostly about all the non-coding stuff. Things like how your company functions, who to talk to about different issues, deep product knowledge and understanding the customers. I actually think transferrable skills grow as well, usually more on the technical side but also on the soft skills side in a generic way. I think the non-transferrable stuff is somewhat unavoidable because of the nature of products, domains, and organizations being meaningfully different.