I agree that a protest can be manifested in many ways. Marching on the streets is but one of them.
Unfortunatelly, protesting by marching can be easily attacked, that's what happened in Hamburg. You just need to pay around 100 people to become violent and destroy some property and fight with the police.
Then they are 'justified' to call the riot police and stop the whole protest and call 'all' of them crazy and violent. It does not matter that there were tens of thousand of people there, just because a very small portion of them turned violent their messsage was mostly silenced.
In essence, protest is a state of mind, an intention to do something that attempts to stop a current situation or to change a current situation.
This article that you wrote is a form of protest.
By educating ourselves outside of schools and corporate media is a form of protest.
Thank you for this article :)