Basically a huge of range of things have to work on large timescales for intelligent life to evolve on a planet.
Which is why intelligent life apart from us could just be absent or very very rare and far away.
Because our solar system didn't end up with the "peas in a pod" pattern, planet formation they also posited a period of violent collisions that stirred things up. Wild, uneducated, and necessarily oversimplifying speculation: perhaps all these early collisions brought water which helped encourage development of life, and led to the formation of Jupiter, which then protected that life's development.
If we see that in all star systems we know that evolved intelligent life (even if there's only 1 we know of) there is a large Jupiter-like planet, and that's very atypical among star systems, that suggests that Jupiter might have increased the probability that intelligent life evolved here.
Basically things have to (not) happen in a series of steps for life to form, even if other things like a rocky planet being situated in the goldilock zone come true. This is apart from a lot of other factors, like not having a big sun etc etc.
All this suggests even if we consider 'Terrestrial mediocrity' to be true. Life could just very very rare across the universe, if not totally absent.
Again, we've only ever observed a single solar system up close.