I've never heard of psilocybin being considered moderately toxic, as there has never been proof of long-term physiological damage in any way - not from what I have seen anyway, so I'm not sure I agree with that. If you can find any sort of scientific literature that demonstrates any possible neurotoxicity of psilocybin, I'd be interested to read about it, though at the moment I'm can't say I buy it. Of course, there is the argument that EVERYTHING can be harmful in a large enough dose, even things like water and oxygen. But one has to consider the practicality of consuming a large enough dose, of whatever it is. With psilocybin, any level of noticeable toxicity seems very unlikely. I do agree with it having the potential of possibly causing long-term psychological distress however, if one were to have a bad trip. One can't deny that. That's why set and setting, along with frequency of use, and yes, dose as well, are generally considered very important.
I am not really a fan of WedMD either, as they seem to have a habit of making something like the common cold sound as malicious as Ebola.
For example:
“It is not a cure all. It is certainly a difficult experience. This is not something people are going to abuse and do all the time because it is not fun,” psychotherapist and psychedelic-research advocate Neal M. Goldsmith, PhD, recently told me.
^I can;t agree with that statement at all. If it did not have the potential to be fun, people would not be using it recreationally to the extent that they do. I do agree with it when he says it is not a cure-all though. That part definitely rings true. A lot of people seem to glorify its potential in that respect.
In any case, I myself have has difficult experiences, along with glowing experiences. I have also had instances where a good trip reversed any psychological distress from a previously experienced bad trip. So it is all subjective and unique from person to person and experience to experience. As far as physical harm? I can't agree at all that it is even close to moderately toxic. Psychologically risky, yes, possibly; but toxic? No.