Cuttin off the streets is also stupid. Why do they do that? to get the attention of people who are already late for work and can´t be bothered to listen to quotes from Das Kapital.
it's way worse than that; they utterly paralyze the country. These protests are huge, thousands and thousands of people cutting out all the key entry/exit points to the city. Very often cutting off the train tracks. They are useless scam, but they are incredibly well-organized and know exactly where to choke production.
What I wrote was an understatement, my apologies. It must be incredibly frustrating for argentinians, but hopefully these people will come to their senses (unlikely though).