I think protests are good since it requires you to go outside and interact with other people, it requires a higher level of commitment than the slacktivism of the 2010s that was so prominent in online spaces. Polls are gamed all the time and social media is dominated by bots, but you cannot fake a large crowd in a protest. If a protest is large enough it creates a force that cannot be easily ignored.
Yes, protests are fertile recruitment grounds. I have inducted many a liberal into leftist thinking after they experience the shocking violence the State is willing to deploy against them for executing what they thought was a guaranteed right.
Of course you can fake a small/large crowd in a protest.
From the top of my head I can think of news reporting both "few (tens of) thousands" vs "hundreds of thousands" (different news reporting different numbers/estimates/etc) in 2025 protests in Serbia/Belgrade, as well as those comparisons of Obama vs Trump inauguration news/photos.
Meanwhile to you as an individual there on the spot - both crowds of say 50K-100K and 1M+ look basically the same = "huge amounts of people in every direction that you look".
Agreed on the slacktivism point. Physical presence means something that bots and polls can't fake. My issue isn't with protesting itself, it's that the assumed impact often seems out of proportion with what's actually being achieved. A crowd showing up doesn't automatically translate to minds changed or policy moved. And crowd sizes can be just as ambiguous as poll numbers when it comes to representing broader sentiment. If the tactics alienate more people than they persuade, visibility alone isn't doing much.