"Majority" (just slightly) is irrelevant. Many tech companies succeed or fail based on whether they are accepted and promoted by a relatively small number of tech savvy opinion influencers. Webmasters and programmers are part of that opinion-influencing group.
For example, Apple is now getting a massive backlash because they have done something wrong to a very small number of programmers:
http://bit.ly/9DyvzY A fair amount of that negative opinion of Apple is going to trickle down to average users even though most people have no clue what an API or C++ is. Because of this incident, Apple will no longer be as immune to criticism and fewer of their followers will be of the "blind lemming" type.
It's not about majority -- it's about a huge amount of dissatisfaction with Google. 45% plus the screenshots I've posted above show that *many* people are very unhappy with Sidewiki.
Other companies don't have the reach to push a tool like this on to the large number of people. Even Microsoft failed (smart tags). Google got away with it so far because most people blindly accept whatever Google does. (Popular opinion: Google can't do anything evil because they say "don't be evil".)
As Sidewiki gets more popular, website owners will notice that people are using Sidewiki instead of registering/commenting on their own websites and the webmasters will begin to figure out what happening.
Like I said, if a few websites block Sidewiki it has no effect on you. You can still use Sidewiki.