Because evolution is a process and a process has steps between a start and an end, the end is the goal;
The phenomenon of biology is the manifestation in the physical reality of life’s process creation. Evolution is a form of creating resilience by compounding on previous states and it is a process that results spontaneously given enough detail is present in the structures and processes that result in life-space.
A somewhat larger explanation is here:
Life causes uncertainty and other problems
The fabric of the universe is made of more than space-time. Surprise!
And of course the bigger picture in the series, starting with:
The meaning of life
The reason for our existence is to defeat time, in life’s eternal battle with it.
… and continuing with the responses to that story that construct more detail.
I guess I see it more as a perpetual avalanche than carefully placed dominoes.
Evolution is not perpetual. It end fairly easy when ecosystems disappear. What we witness as the phenomenon of biology is a fascicle of evolutionary processes and many of the stems in the fascicle are very short and dead.
It is also not an avalanche. There are rules and change drips in an evolutionary process.