The point still stands. Where's the line between how much value in resources a "specialist" title is worth? 50mp? 100mp? What factions get to use them? who doesn't? etc
"Specialist" isn't a some sort of special rank, it's a statement of function. You've got generalist units which do a bit of everything, and specialist units that are very good at one or two things and are not good at anything else.
Take the OKW Panzer IV and the Jagdpanzer IV. They cost almost the same. The Jagdpanzer IV is far better than the OKW P4 at fighting armour, but the OKW Panzer IV can fight infantry too. Specialist versus generalist.
Obersoldaten are anti-infantry specialists: they can't do anything to armor. Guards are generalists: they've got solid anti-infantry performance and some light anti-armour weaponary.
Therefore Obers should probably outperform Guards in infantry combat, and they usually just about do.