I've seen that as well. I've also seen optimism doom teams in the forms of failing to anticipate obstacles, making unreasonable promises in binding documents, and underestimating project effort.
Seems like being objective and calibrating your expectations appropriately based on the risks you can or can't accept, or the trade-offs you do or don't get to make and avoiding bias or emotional attachments is pretty awfully difficult for humans (even very bright, talented ones) to do.
Seems like being objective and calibrating your expectations appropriately based on the risks you can or can't accept, or the trade-offs you do or don't get to make and avoiding bias or emotional attachments is pretty awfully difficult for humans (even very bright, talented ones) to do.