[Nasrudith]

For better or worse economies of scale with increasingly large upfront costs and low unit cost are what sustainably drive dominance and thus lead to a "monoculture" as a better strategy until they squander it sufficiently to be overtaken.

The truism is a bit off as well given the difference between "defacto standard" and "monoculture".

Of course not all monocultures are equal as well - commerical monopoly vertical intergrated, horizontal like ARM style designs made by others, open standards used by all, etc.