[ormaaj]

Yes a standard agreement such as that is expected and customary, and they have it for good reasons. However it is not strictly required in order to make use of user-submitted content.

Also as I have pointed out in other comments, this is a contract, and as such there are quite a few reasons that a contract like this might not be binding. One major weakness is its semblance to a "click through agreement". An agreement hidden in the footer of a website or in the fine print on a registration page is even more subtle than that and it's entirely possible build a case against implicit agreements that automatically kick in through mere use of a web service. There is considerable case law devoted to this and it's gone both ways - depending on the specific facts of the case, who makes the better argument, and the disposition of the judge.