Well I would have to disagree with that, especially on the internet!
I argue with people that are wrong, even people I KNOW I have no chance of changing their mind... Because there is a good chance other people will see it who are not so closed minded and possibly be able to change one random persons mind and open their eyes to the truth!
I do the same thing. I think of it as planting seeds. It also has helped my debating skills immeasurably over the past 20 years. Its futile I know, but its still fun calling ppl out on their idiocy.
AMEN!