I lean toward Tucker's assessment, with a little pinch of "but..." thrown in.

In the 40+ years I've been growing, I have heard a lot of comments about charcoal "sweetening" the mix - helping purify it by trapping wastes. However, in order to be an efficient "trap" for such chemical species, the charcoal would have to be "activated", which greatly enhances the number of adsorption sites.

I suspect that the mere heat conversion from wood to charcoal does "activate" it to some degree - primarily at the surface I imagine - but its probably orders-of-magnitude less than that seen on truly activated carbon, drastically limitng its trapping capacity.

Having said that, I will add that all solid potting media components still absorb and trap minerals and wastes, which is why we need to repot regularly, even iof the medium has not significantly decomposed, and I doubt that the charcoal does much to extend the time a mix stays viable.