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.
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.