Your 2 cents are spot on!Fertilizer wars! Gotta love 'em.
I couldn't tell you whether the science/reasoning behind @MichaelS posts is valid or not. But I do know that scientists have shown that high concentrations of Phosphorus inhibit the growth of mycorrhizal fungi. As further anecdotal evidence, I have never seen better mycorrhizal growth then when I use a completely organic fertilizer regimen. That's my two cents.