yeah, i think this is a real concern. the diagrams are all attached to code by design so we can tell if something has drifted (e.g. can model a diagram node in a sense as a code forge "comment"; building upon some great work from e.g. gitlab here!).
there's a separate problem here re: multiple sources of truth (e.g. Linear for a spec) that you're also getting at. in my own experience, whiteboard is still quite helpful when it's important to understand the change going in (which isn't every single one!).
in the future, we plan to deliver (1) affordances to capture the spec planning process in the whiteboard so you can iterate more flexibly / in more ways, and (2) will also ship a hosted product so this can be multiplayer - which will help resolve that source-of-truth issue, we hope.