Well I would not call SelfHacked's website conventional medicine. It's pretty alternative. So if SelfHacked is calling the OAT a scam, it's not looking good for that test.
SelfHacked very carefully worded their article by saying "Many skeptics say that OAT is a scam. It will set you back around $250 or more, and you will likely not be any better off for doing it", but if you scroll further down their page, they talk about which markers are reliable, etc., on six separate pages.
Of course the vast majority of people won't need an OAT test, but we ain't the 'vast majority'. We're a tiny minority whose disease happens to be made up of many of the issues (gut, mitochondrial, methylation, etc) that an OAT can at least begin to address.
I had one done in September 2018, and as of a month ago, it may have just saved my life. While two doctors missed it (as did I), an acupuncturist I saw last month noted that my c. difficile marker was just two points away from being officially 'High'. And that was two years ago.
Finally, I have an explanation for 19 months of diarrhea (80% of the time) and the resultant malabsorption, inflammation, and weight loss. (I had a stool test done in July of last year which came back clean. Little did I know then that the stool test has a 20% false negative rate.)
Anyway, I started s. boulardii and Lactobacillus rhamnosus GG 3 weeks ago, and my diarrhea stopped in 2-3 days.