The American Gastroenterology Association is paid to advocate for its members, so it's reasonable to assume they'll endorse anything that will make gastroenterologists more relevant. But there are limits; they won't endorse fraud.
Probiotics certainly claim to be about our gut microbiome, and that is important, but most of what it may or may not impact is unknown and that is how those ridiculous yogurts and supplements get sold - they profit from the 'god of the gaps.' Of course, it's not legally liable fraud, it is actually government approved. President Bill Clinton rewarded his donors, and constituents in his political party who overwhelmingly embraced alternatives to medicine, in 1994 by exempting supplements from FDA rules. They can't claim to cure cancer, but they can claim to do anything short of that if they just include a disclaimer that says no scientist agrees with any of their nonsense. No clinical trials necessary, and it has created a $35 billion industry based on no science.
The unknown is how expensive yogurts and pills and even unnecessary fecal transplants have become such a huge industry. Like all supplements, they don't need to show it works, they just need to write testimonials by people claiming it works.
The American Gastroenterology Association does not say probiotics are fraud, these groups have to use soft, wobbly language, so they instead note evidence is "unclear" but in the world of medicine you can't get a product approved if it's unclear, it has to be clear or it does not work.
Even Clostridioides difficile infections, which blast our microbiomes to smithereens and therefore are considered the sweet spot for probiotic hype, should only include probiotics in a clinical trial, presumably when lack of a fecal transplant won't be harmful to the patient.
As Science Based Medicine wrote, there is no evidence it will do any good so far. "Five trials with different products were identified, and because they were so different (in terms of patient populations and other considerations) the results couldn’t be combined. Due to high risk of bias (unpublished trials) and mixed results (one product appeared to increase C. difficile infection recurrence)" - so no evidence it helps and some it hurts.
Probiotics are absolutely a sign of socioeconomic privilege so if you have the wealth and like the taste of the yogurt or whatever, yayyyyy capitalism, but don't tell people the science is there. It simply isn't.
