To be honest I think (I hope) some people are taking the majority of posts out of context. It's not that maintaining possession isn't beneficial, I again assume people are getting frustrated of the lack of 'line penetrating' passes.
There have been a number of games when we haven't played a penetrating pass against the line. To be fair it is what Gaston is superb at and we saw it with our first goal.
The reason most teams maintain possession around their own area(or high defensive line) is to draw any initial press from the opposition and take out each line (attacking - strikers, wingers and holding players CDMs,CMs) with no more than two passes. It doesn't always work and you can now see Barcelona play a number of diagonal balls to cut out the first pressing line.