Doping

Basically having only a fixed limit or ratio with no regard to what a persons natural 'base' levels are is unfair and effectively allows the unscrupulous to freely manipulate those levels with illegal performance enhancing drugs provided they stay below the arbitrary limits.

If testing T/E ratio just once were the only tool in the drug tester's box, you might be onto something, but longitudinal studies of T/E and selective testing (isotope ratio) for synthetic [epi]testosterone make manipulation of T/E detectable. Tests are available both for synthetic testosterone itself and synthetic epitestosterone used as a masking agent, i.e.taking epitestosterone to increase the E in the T/E test when T is elevated by either T doping or other androgen doping which causes elevated T, so that an elevated T/E doesn't provoke further analysis. Although elevated T/E is the usual trigger for isotope ratio testing, a doper manipulating T/E cannot be certain that is the only trigger.