[lolinder]

> I've just left a startup company who's entire backend was written ... by an agency. ... A new dev team was created to take over and it was a disaster.

I honestly think these are the important bits of this story. The startup outsourced their backend to an agency, then tried to replace the agency with a brand new internal dev team.

There's no way that story ends well, regardless of the paradigm the agency chose or how skilled they might have been (probably not very). Every codebase is unmaintainable when the team that built it is suddenly replaced.

Peter Naur had a lot to say about this in Programming as Theory Building [0]:

> The extended life of a program according to these notions depends on the taking over by new generations of programmers of the theory of the program. For a new programmer to come to possess an existing theory of a program it is insufficient that he or she has the opportunity to become familiar with the program text and other documentation. What is required is that the new programmer has the opportunity to work in close contact with the programmers who already possess the theory, so as to be able to become familiar with the place of the program in the wider context of the relevant real world situations and so as to acquire the knowledge of how the program works and how unusual program reactions and program modifications are handled within the program theory.

[0] https://gist.github.com/onlurking/fc5c81d18cfce9ff81bc968a7f...