Why would anyone do this?
For one, suspended reality allows us to be creative and simulate outcomes that otherwise would not occur in real life.
But also, it can occur under information asymmetry. If something seems fake to me, but I am not sure if _you_ believe it is fake or not (and vice versa), we both might pretend something is real for the sake of not offending one another.
This segues into another of Weinstein's terms (originally from Timur Kuran) called "preference falsification": if no one has to falsify their beliefs, we might just _state_ things we don't actually believe in, since we don't know what other people actually believe, and we don't want to run the risk of being ostracized.
Overall, these two concepts explain how otherwise tenuous theories can be believed (or at least stated to be believed) by large groups of people.