I hate this expression. Absolutely hate it. I have a few friends that will post this whenever someone (including me) mentions anything that didn't go right.
Aside from the fact that it marginalizes populations based on geography (which is not correct as there are lots of people in the 'first world' that live in extreme poverty), it also is disturbing to think that anyone is not allowed to complain unless they have no shelter/food or basic needs met.
If people don't show that things aren't so rosy, others will get the impression that things are always wonderful (which they can't possibly be). There are so many issues that if others knew what one was going through, things wouldn't be so lonely. I had a friend who finally posted about her infertility and all these people came out to let her know they too had fertility issues and now I think several meet on a regular basis to support each other.
Just this weekend, my plane got grounded due to conditions at the destination airport. I posted this issue on FB and got #firstworldproblems as a response. Yup, not the same as no food or shelter, but still something that was frustrating to me. I've had people think my life is great because I travel a lot, but sometimes travel = problems.
End of rant. I just wish people would stop with the #firstworldproblems.