My experience this year has been very similar to those posted about. We've only been involved for 3 years, but yes, this year there seems to be more folks who don't respect the "blankets on the bleachers". But I will still say this, for every bad experience, I've had at least 3 good ones, with people who were happy to let me have a temporary seat when I moved to get a better view of one of my boys' matches, and folks who passed me towel when I needed one to wrap an ice pack.
My biggest rant is to the folks who think the Head Table's instructions asking everyone on the mats to kneel don't apply to them! I finally learned that it does me no good to be matside, my kids don't hear me, if they do, it's just a distraction from what their coaches are telling them, and the best place for me is in the stands. However, I would still like to get a good view, and I can't count the number of times I've heard the Head Table asking everyone to take a knee, and those down there will turn around, look at the source of the announcement, turn back around and remain standing.