Reasonable yes, but an amusing thing resulted from it. Carrying everything you'd need for adventuring took a lot of weight. The bare necessities are 66 pounds on their own, almost two thirds an 18 str character's maximum unencumbered load, without factoring in money or weapons and armor, which could easily eat up the remaining 34 pounds.
I think the inflated numbers are mostly so the party doesn't need a wagon to haul around their stuff/treasure everywhere. Yeah it's a little ridiculous, but the only other solution was to completely disregard the encumbrance rules in full.