There are many Goldilocks planets, perfect for sustaining life, but yet no signs of intelligent life have been found. The Gaian Bottleneck hypothesis asserts that the temporal aspect of habitability is the bigger hurdle:
Early life is fragile, so we believe it rarely evolves quickly enough to survive.”
“Most early planetary environments are unstable. To produce a habitable planet, life forms need to regulate greenhouse gases such as water and carbon dioxide to keep surface temperatures stable.”
About four billion years ago, Earth, Venus, and Mars may have all been habitable. However, a billion years or so after formation, Venus turned into a hothouse and Mars froze into an icebox.
Early microbial life on Venus and Mars, if there was any, failed to stabilize the rapidly changing environment, said Charley Lineweaver from ANU.
“Life on Earth probably played a leading role in stabilizing the planet’s climate,” he said. (Link)