Of analogies and monocultures
Analogies are great tools. Their goal is to explain stuff pertaining to a certain context to someone which has insufficient knowledge about that context, but sufficient knowledge about another one where similar stuff happens.
Basically you extract meta-stuff and put it in a known context so that you can make a point. Analogies do not make a point by themselves. Ever.
Take for example this analogy rebuttal, wherein software monocultures are equated to Ireland physical monoculture which led to a disaster.
I think that the analogy still makes some sense if you apply it to the same scale.
The biological case "Ireland farmed one species of potatoes. Said potatoes went irrevocably compromised. Ireland hungered to death." cannot be compared to a single corporate IT infrastructure.
Imagine that (admittedly non-realistic) case: "Ireland relies solely on the Microsoft ecosystem. Said ecosystem gets massively infected by a critically damaging virus. Ireland economy grinds to a screeching halt.", that is the proper analogy. If half of the companies in the country had its IT infrastructure based on another system, then half of the country would still run. Just as half of the potatoes would be palatable.
At the other end of the scale, a single corporate IT infrastructure with heterogeneous ecosystem would be more like a single farmer cropping multiple species of potatoes. It can indeed get costly as at this scale managing the peculiarities of each species (soil, maturity...) could become complicated. Yet it can still be quite worth it.
Real life example: when McAfee AV false-positived and quarantined some kernel32.sys or whatever, turning our Windows machines into useless boxes, we could still save the day thanks to our few Linux and Mac machines.
So, making a point and explaining it through analogy is valid, yet analogies do not make a point by themselves. More often than not it is a double-edged sword that might bite back while you end up being sidetracked in endless arguments irrelevant to the initial context, and therefore issue.
Therefore, make your point first. Explain the context as best as you can. Then and only then enlighten the context with a thoroughly thought analogy. Only by keeping both clearly separate can you identify the analogy shortcomings (or lack thereof).
