@Sandra856
It was Clara Liang, Airbnb Director of Product, who stated in the June 29th 2018 Q&A (with Brian Chesky sitting beside her, nodding in agreement) that guests should not be allowed to leave a review if they never checked in, and that if it did somehow happen, that hosts could call CX to have the review removed.
However, within days, Airbnb had done a complete U-turn on that and said it wasn't correct, and that guests can leave a review, even if they've never laid eyes on a place. They also removed the relevant clip of Ms Liang making the statement from the Q&A video, and deleted the associated paragraph from their written synopsis of the event.
The following is a very long discussion on the issue, but if you scan the first and last few pages of the thread, it gives a general overview of what transpired.
https://community.withairbnb.com/t5/Hosting/To-Clara-Liang-Product-Director-Last-min-cancellation-be...