I challenge you to post one example of the accepted Theory of Evolution that is philosophical.
Just one.
When the question is asked, why can't microevolution lead to macroevolution, that is a philosophical question which shows the philosophical part of evolution.
Not only have you failed in your understanding of philosophy, the question you ask, "
why can't microevolution lead to macroevolution", is not an example of the accepted Theory of Evolution.
First, lets get the actual scientific terms correctly defined.
Macroevolution is used to refer to any evolutionary change
at or above the level of species. It means
at least the splitting of a species into two (speciation, or
cladogenesis, from the Greek meaning "the origin of a branch". Any changes that occur at higher levels, such as the evolution of new families, phyla or genera, are
also therefore macroevolution, but the term is not restricted to those higher levels. It often also means long-term trends or biases in evolution of higher taxonomic levels.
Microevolution refers to any evolutionary change
below the level of species, and refers to changes in the frequency within a population or a species of its alleles (alternative genes) and their effects on the form, or phenotype, of organisms that make up that population or species. It can also apply to changes within species that are not genetic.
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Source)
Second, while there may be philosophical debate among scientists concerning whether or not Macroevolution and Microevolution are reductionist or non-reductionist, neither of these tenets are central to the actual Theory of Evolution. Nor will either one be until it moves beyond the simple philosophical questions, and into empirical data. As actual Micro and Macro evolution have done already.