Why is the line always blamed when you lose a football game?

I don't think that it's fair when we the linemen get blamed after a lost game because if it wasn't for us, scoring would be practically impossible. Some of the running backs at times run backwards and sometimes are also slow getting through the whole that we the linemen work are butts off to make. I know that we can make mistakes like not blocking correctly or even not blocking at all but when we do block correctly it's very hard to stop us from driving you out of the play. Going back to my topic though, it's not all our fault. A loss is a loss and not just one person is the one to blame because a team was out there and a team loses and wins together. Still i get so frustrated when it is the lines fault and i'll be the first one to admit it if we played a horrible game than i know that some of that was our fault.