Hylemorphism explains becoming.
The activity proper to life is not a kind of becoming.
True, there is a clear sense in which (some) living things come to be – biological entities go through stages of maturity and decline; but living differs from maturing in that the latter is a way of coming to be while the other is not. Nevertheless, Aristotle wants to explain life by exactly the same principles as he uses to explain becoming. The soul is numerically identical to a principle which was only introduced to serve as the terminus of becoming, imperfectly present during the becoming. Irrespective of what we think of hylemorphism, it’s worth asking how the doctrine is not reductive naturalism, or why it does not seek to explain dissimilar proper effects through an identical cause.