With new contributors joining the project, it might be difficult to explain all the historical decisions we made over time.
It's also not easy to remember all of those decisions over time, at this point, Flow has 26 sub-repositories.
To solve that problem all major architectural decisions should be described in ADR documents that every single contributor must follow with no exceptions.
The only way to merge a code that is against an existing ADR is to write a new ADR that overrides the previous one.