Protests are rarely about setting policy. They're about voicing their disagreement. Even if people at Occupy Wallstreet (and many other protests) can't agree on the solution, they do tend to agree on the problem.
Grassroots activism used to be better organised. Trade unions and other working-class organisations provided structure and institutional expertise. Discontent could be directed as part of a broader strategic campaign. The atomization of society has diminished the influence of these organisations. Most activism today is disorganised and strategically inept, simply because the instigators are inexperienced and lack the support of a wider network.
I believe cases like these are just spotlights on how different we as humans tend to think while assuming those grouped around us tend to be more similar than in actuality.