Never worked in tech so I find this mindset really alien. Why no specialisation and separation of duties? Why not have someone really good on the business side and someone else who is really good at coding?
The business-only guy won't see the limitations and possibilities of code, while the programming-only guy won't see where the business side is flexible or where it is rigid, thus the optimal solutions can take a long time to find.
The business side might also be prone to specifying X-Y problems, which can be very difficult to spot if you're not into the business side.
At least in my experience, having significant domain experience in our dev department has been a super power of sorts, allowing us to punch well above our weight.
edit: I didn't have any domain knowledge when I started, but I was willing to learn.
Sometimes the business only has a high level goal in mind and it is up to the developer to invent a solution, keeping in mind how the end user will interact with the system in their day to day work, and foresee potential issues in how the changes would impact other systems and business rules and so on. The developer has low level visibility of systems that are not readily apparent to business people. It is necessary for us developers to hide some of that complexity from the business. Some backends are very complex webs of business rules.
The developer needs to have some bigger understanding of it all, otherwise they are reduced to a code monkey who implements spoon-fed acceptance criteria from Jira tickets, makes stupid mistakes that break other functionality and systems, and won't recognize various issues that were not apparent to the business person who originally wrote the AC's. Basically we need developers to collaborate with the business to design and develop solutions properly.