I look at that link and the burgers they have on the right have grill marks on them but they did not get those grill marks on the mat. Look how the grill marks are indented into the meat. That only happens if they are sitting directly on the grill grates, not on a grill mat that is flat. I was able to get a little bit of a grill mark, but not nearly what I could get with the meat right over the coals.
I'll admit, they are probably really good for fish, but so is my
fish and veggie grill pan.