Yes, for sure there are several whacked out things in the rules, this being one of them.

If that bothers you but you still want to stick to the rules, you can try the rule tweaks suggested in Arsenal:
• Ignore armor encumbrance entirely if a character is simply wearing a single armor item (even if that’s a full body armor suit). Only apply encumbrance when a character is stacking armor or using a
lot of armor accessories (helmet, shield, forearm guards, etc.).
• Allow characters to buy customized armor that is specially-tailored for their specific bodies (much like how military-grade armor is fit to each person). Custom-fit armor could either ignore encumbrance entirely, or increase the armor allowance to Body x 3.