I read things like this so often. As if all that was needed was "any bacteria". Sure, fish poop has some bacteria in it. So does human poop but I don't see anyone recommending that as a supplement! Different bacteria live in different environments, and the inside of a fish gut is quite different from the open ocean.
The question is, how do we inoculate the right bacteria, not "any bacteria". Aside from live rock, I have seen no evidence that anything else provides the bacteria that make up the community in a mature reef tank. I mean, if fish poop was all that was needed, wouldnt all tanks have the same bacteria? We all have fish poop.
And I'm not really picking on your suggestion of fish poop, its just funny to see how many times I can write fish poop in one post

I'm really picking on the idea that "the bacteria will just show up somehow", whether its through fish poop or other unspecified means.