That argument doesn't work if it's a monopoly or a near-monopoly, which Wikipedia is. Also YouTube etc.
People have set up alternative data sources to Wikipedia. Conservapedia has existed for years. Its relatively smaller size says more about its relative utility then about anything ill Wikipedia has done.
The other reason it didn't really work out well is that people need an audience. Voat was and is much smaller than reddit, so they had less reach. What I'm trying to say is, is that it's not a technical challenge, those have been solved already. It's people with extreme views who want to be able to express themselves where those views are not tolerated.
I'll join the protests once they actually start censoring, but if it's just like hey: don't be an asshole or you can just be an asshole somewhere else... I'm fine with it.