Like it said in the quote, it fixes dirty cats. If your cat is melted, missing chunks or you are burning a lot of oil it may not help. But it's $29 vrs $1029. It may have been worth it as it cleaned other things but unfortunately wasn't able to save your cat.
I would Put in a cleaner if you use a bit of oil. At this point you should also change your PCV valve. This is good especially when you first find your oil is disappearing.
I know some people are a little bit afraid of the lacquer thinner, so i put a few different options that say they are meant for cars. I personally don't know the others, but have used lacquer thinner at 1/2 strength with no drawbacks.