I've only used the agentic tools a bit, but I've found that they're able to generate code at a velocity that I struggle to keep in my head. The development loop also doesn't require me to interact with the code as much, so I have worse retention of things like which functions are in which file, what helper functions already exist, etc.
It's less that I can't understand, and more that my context on the code is very weak.
I might have to try this. Without having tried it, it feels like the context I think I lack is more nitty gritty than would be exposed like this. It's not like I'm unsure of how a request ends up in a database transaction, but more "do we need or already have an abstraction over paging in database queries?". It doesn't feel like mermaid diagrams or design documents would include that, but I'm open to being wrong there.
It's less that I can't understand, and more that my context on the code is very weak.