The same principle as that you have to post something to see the hidden content only with likes.
if every person had to like it would be overkill and pointless so i would suggest 1/3 is 33,3333.... % probability that the person must give a like in addition to the post, so you also reduce by 33.3333... % that there are so many leecher and everyone has something of.
I think the point of "contributing" it's posting stuff without trying to get something else, just to contribute to the community + it probably will crash the servers with the "x1 porn hit" threads