> They want to somehow have every single person in a 3 block radius park on the perimeter of that area? And this is somehow supposed to make things better?

Very few people in Barcelona own cars. Residents will have access to drop off things, but not parking.

> I'm really tired of anti-car advocates that have just a single idea: Make people too miserable to use a car, and maybe then there will be less cars

European cities tend to be pretty miserable places for cars by default, for the anti-car advocates it would generally be enough to stop subsidising cars.