For an amusing view of how the world would be without the lying, watch the movie The Invention of Lying.
And then there are lies like the one in this example. Where not only the lie is self-serving, but it had the potential to hurt other people. Imagine you're one of the other guys using the service and you try to talk to one of those fake profiles. You get your hopes up and then the fake profile cuts communication or plays a practical joke and invites you on a date. Don't you think that's at least a little cruel?
Lying is a tool, it can be used for good or bad.
Why are your examples cruel?
Someone learns that they need to address their weight problems before it affects their health badly or if they want to woo you or whatever.
Someone else learns that they receive presents not because they've been good but because people regard them; I was going to say love instead of regard but that's not always true.
Sure you can say things in cruel ways ...
That's precisely the point. Here lying was done for personal gains.
Ok, not hard to imagine. I'm using the service, I message one of those fake profiles (amongst the other multiple of profiles I message). I get no response, figure she is not interested and move on (just like most other messages to profiles).
Yes I think it's cruel if they used them to play jokes. Worse yet is that I know people who are using this for financial gain. They setup fake profiles in dating sites, and respond with messages containing premium rate phone lines. They made millions, got fined in one country but the profits made elsewhere made up for that.
Article says: "My two friends operated the 50 accounts while I found the prettiest ..."