I agree with Tim. This reminds me of the "three powers" (and I know this is not a State and there is no such thing as a "government"). *Division* of work and functions is
a) more transparent (there is not even the remote possibility of dictatorship, and mistakes are mistakes in only one part of the project). b) easier to maintain (someone with just one function may be removed as there will easily be substitutes. Someone for just one function is more easily found than for two). c) easier to work in (the person needs only care about "one" aspect of the project).
My 2c. I probably ought to have quoted Tim, but my mail client is far away and editing is a pain....
Pedro.