People frequently say this (right down to the cliché about how lucky he was to be facing the British), but it's obviously untrue. Gandhi's great insight was that nonviolent resistance is more effective than violent resistance. He is increasingly being proven correct. (Popular movements pretty much instantly lose their legitimacy when they turn violent.) That some authorities massacre people doesn't refute it.
Let's not forget that Gandhi's techniques were considered ridiculous and guaranteed to lose by most people at the time. It was only once he won that the "obvious" position had to be revised to "well of course it worked in that situation, but..."
Gandhi didn't invent these ideas but he demonstrated their practicality in a shockingly counterintuitive way. If his techniques truly weren't generalizable to anything else, they wouldn't have worked for him either.