Great question!
The answer is: there are basically no rules in regards to how, when, and why a company chooses to invest their money. Companies are free to be as rational or irrational as the human beings making the decisions behind the scenes. It can be as simple as they do not want to spend more than "X" amount for "X" situation and would rather have "X" venture up and running on its own and, should it fail they do not want it to harm "X" parent company.
But, that's just speculation based on common sense.