I've been using one for about a year now on all my cases. For some it will be viewed as a worthless step because you can tell when the primer seats too easily.
Using this tool is a piece of cake. When I have a set of de-primed cases, nose down in either a loading block or box, I merely run up and down the rows with the large -NO GO end and check the pockets. No wasted primers which can add up over time.
I just see it as another step in case inspection and how much of that one does is up to them. Some people merely pick up their brass, shake off the dirt, and reload it. Others take pains to clean it, inspect well for flaws (including loose primer pockets) and only then reload the brass that is "worthy". There are those that also fall somewhere in between.
When it comes to tools for reloading, a tool like this makes far more sense to the "masses" than a "Thousand Dollar Scale" capable of measuring the weight of "Mosquito Poop".