> Fisher's Fundamental Theorem: The better adapted a system is to a particular environment, the less adaptable it is to new environments. -- Gerald Weinberg,"The Psychology of Computer Programming"
It's something everyone should consider in making critical design decisions. Your adaptable, modular system has some risks (particularly in terms of meeting performance targets, increased cost due to increased complexity), but the monolithic system has its own risks (less adaptable to changing requirements, potentially more fragile against attack or damage). Which you choose depends on many variables including your risk profile and anticipated need for change in the future.
If we consider any possible solution, we can obviously imagine adding a completely spurious detail.
At least in the case of code, this isn't true. The variability comes in terms of change to the system, rather than the running of the system. i.e., if I simplify a process to be less modular and more monolithic, making it more efficient, that also makes it more purpose-built and less flexible. The "risk" increases of running up against a change that needs to be made but is intractably onerous. There's always a tradeoff.