Here's an example: WoW comes out and I meet people while forming up groups for dungeons, I get the people who are good / fun to be around on my friends list and try to run with them whenever I can.
WoW introduces the new and amazing LFD, and after a few years the people I meet left the game. I'm now using the LFD for groups and I don't even bother trying to get a group together on my server because it's filled with "LOL! Use LFD noob!" trash.
My friends list has shrunk to one maybe two people, and those folks are in my GUILD! I can't even get friends because the LFD goes cross server, so those awesome people I liked? Can't play with them anymore.
LFD killed community for me, you're lucky or blind if you didn't see it.