I have a theory that intelligence isn't particularly rare however the rate of development may be. It has long been alluded to in Sci-Fi that humanity's rate of development is fast (Humans vs Vulcans, Halo universe, etc). I imagine that one of the great barriers is that a civilisation with a lower rate of development may stuck in an industrial type era unable to progress before doing irreparable damage to their enviro…
To be fair, even with our (fast paced?) rate of development we have a hard time to tech fast enough to outrun the industrial damage. On the other hand, only total extinction might be truly "irreparable".
You don't see kids in coal mines in England but you do see people dipping circuit boards in vats of acid without protective equipment in India. We may be investing in renewables in the US and Europe but we still flood parts of Africa and the Sea with crude oil and all that lithium doesn't mine itself.
The "Industrial Age" may be over but the damage is still being done and all the shiny new tech is largely window dressing. It's also not yet clear that the shiny post-Industrialism can easily exist without the rest of the world perpetually playing "catch-up" (i.e. whether it really is catching up) as our quality of living heavily hinges on underpaying other countries for resources and labor.