if I want to meet up with someone, wouldn't I just give them an exact location? if the nearest landmark is 5 miles away I don't see how that would be useful.
What if we have gathered just the right amount of landmarks from the area, so it's pretty likely that all the well known places to meet at are there already?
Naturally if you are in a rural area far away from any kinds of "real" landmarks, this will not help you. But by definition, such areas will have low number of potential users as well. We think this works well for a lot of people a lot of the time.
http://blog.geckosmsapp.com/hello-world-what-is-a-landmark
So we hopefully have the right McDonald's already mapped for you.