Wow I went Inside Baseball (tm) today on magnitudes. Magnitudes were originally designed to be purely observational, purely relative measurements, relative to a standard star. But then once you go off-course and define absolute magnitudes (gasp) and then even farther off and define bolometric magnitudes (double gasp), the system is no longer relative to anything! It depends on (imprecise) distance estimates and (wrong) stellar models. So you get many absurdities, like that Vega is not zero in any Vega-relative absolute or bolometric magnitude system. I think maybe we've lost our way! And not because magnitudes are obtuse; apparent magnitudes and colors make lots of sense! We lost our way when we tried to extend this to cover luminosities of various kinds.
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