Another thing is that boredom is not a property of a film, like colour or length is. You cannot point to a film and say "That is objectively speaking a boring film." I thought The Avengers (Joss Whedon 2012) was incredibly boring but I am not sure the cheerleaders of boredom would tell me off for saying that, or argue that it is good for me to experience that boredom. What they mean are films like The Turin Horse (Béla Tarr 2011) or Jeanne Dielman, 23, Quai du Commerce, 1080 Bruxelles (Chantal Akerman 1975), long films where not much is happening on the surface. But I do not find either of them boring. Would the boredom adherents consider it a failure if a film did not bore them? As it would be absurd, probably not, but it is not more absurd than the original argument that there are films that are objectively boring and as such good for you. Sometimes it seems people feel guilty about being bored, but they should not. Being bored is just as valid as being overwhelmed, amused or disappointed.
I suppose the argument the pro-boredom crown is making is that boredom is an alienating effect, in the Brechtian sense, but I am highly sceptical of Brechtian alienation too. There are several reasons for this, and one is that I see no reason to assume that an alienated audience will think in new ways or be politically enlightened, just because of the alienation. I also think that many get confused about what alienating effects really are and which films have them, but that is for a later post.
Finding something boring is not a personal flaw but a natural, subjective reaction, and I am not convinced that we do art any favours when we praise it for being boring.
Bergman speaks of Antonioni on several occasions. The quote above was from an interview John Simon did with him in 1971. It has been re-published in Ingmar Bergman: Interviews (2007).