The idea that 308 can do most everthing is probably fairly accurate. But for me I collect guns not based on what caliber they are, but for the historical significants of the actual gun. Caliber is almost irrelevant. My american Krags happen to be 30-40. My Enfields are 303. The MAS is 7.5 x 54 etc etc. All close to being an equivalent to 308win, but I wouldn't rechamber just to reduce the number of calibers I load for.
I guess that brings up the obvious question why anybody wants countless numbers of guns that essentially do the same thing. But I don't have time to ponder that, I need to get some 8 x 50r, 8mm Lebel, and 8 x 57 reloaded today.