Some users (the smallest ones) care about every single upvote they get. If you upvote someone, it may happen that this guy will look at your account and that he will read some of your articles. So I got an idea to test this... I paid for delegation of 1000 SP and I give upvotes to many people. And some of them look at my articles. I started doing this few weeks ago and even this article started to get upvotes and comments despite the fact it is 8 months old.
I am just testing this way of gaining readers. Value of their upvotes is very negligible, but they are genuine readers... and that is what I care about.