Assigning personal responsibility to someone else is a bit similar to giving a Facebook like. It appears encouraging (thus presenting a good image for your fellow encouragers, and is unlikely to invite scrutiny), and requires very little effort on your part aside from a pat on the back. In some cases, you're even allowed a rebuttal if the person you're telling to be the change isn't convinced.
What the phrase ignores - possibly intentionally - is the issue of elephants in the room. People generally aren't receptive to change, especially in organisational contexts. Stories about how people have tried to affect positive change in their workplace or social environment are plentiful, and the same goes for their failures. The truth is that while people want you to change, the enthusiasm ends as soon as it starts affecting them, and then limits and boundaries are placed on just how much change you're allowed to be. This continues to the point where any attempt at change on your part becomes ineffective and toothless, and you're no better off than before, aside from a new reputation for being a nitpicky troublemaker. Ultimately, the message boils down to "Thanks for trying. Assimilate or leave. It's not like we'd be significantly affected no matter what you choose."
You can be the change you want to be - everyone else will be making sure that over time, you won't want it anymore. Then you can join them in the ranks of the disaffected.
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