You microbiome is more akin to a forest than a farm. You can't just plant potatoes (or whatever) and assume that it will get balanced. Sometimes things like this do help, but sometimes they don't. Fertilizer makes plants grow, but it can have unintended consequences. (For example, runoff leading to bacterial blooms in a watershed.) The gut is an ecology, hence the difficulty of determining one-size-fits all fixes to a complex ecosystem.