I guess it depends on your ability to stand up a credible alternative to whatever organization it is that you wish to force change. If you can't stand up a credible alternative, then all you really can do is try and change the organization from the inside.Gotta say the whole "if you don't like it then join" idea is one of most absurd things I've ever seen. Imagine applying that logic to anything else in life...
"If you don't like the BNP, the join and try to make them less racist"
"If you don't like the way McD's taste, then get a job there and make it taste better."
"If you don't like Putin, then become a Russian citizen and vote him out"
"If you don't like Ahab's opinions, then engage him in conversation and change his mind."
None of these things are good ideas.