The point is, the photo is not deleted, even if you remove it from your page. This has been at trial, and the plaintants lost. Your posts are not deleted but they can be removed from public view. Yes, you grant them license, they do not own it, they own license to it and can sell subordinate licenses. I lost revenue from one image I had licensed each year to a cruise line for their cruise catalogs. It was not for a lot but did received a few hundred every year they used it until they bought a license from a stock company that markets the FB images. I had uploaded an image, which appeared small and low res as normal but the original file uploaded was large enough for the print catalog use. So they use the image, and pay me nothing. This is not unusual so the few times I post images they are all degraded intentionally.
I am pretty familiar with IP law, having been in dozens of suits in the recording industry in my 25 years as a studio owner/producer and recording engineer. Being the person/company that produced major records, whenever there was a case that was related to the record, I was named in the cases. Never lost one that went to court, most are known to be groundless nuisance cases but a few big ones that did go to trial became national headlines. Copyright and license law is essentially the same with photography and songwriting. The case of FB that involved that terms of service agreement was when a deleted account owner tried to have stored data removed from the databases even though the account had been deleted from public view and her view. FB won. The US government had a stake in it also, they do not want their access to that data on individuals to disappear either. If it is on the servers, the license granted is in force even if the public account is not visible.