It is true that the encumbrance rules are prefaced with "don't use these rules unless you need them," but what does that say about the rules? Would it be so bad to have a system of hard and fast rules that were always in effect? And not a mishmash of rules that only sometimes come up (in this case, to adjudicate disputes).
Like I get that it does say they're not to be used and checked all the time, but why is that a good thing?
Exactly. Why have a rule whose sole purpose is "use this to resolve a dispute (rather than using common sense)?" Why make that rule in turn be so complicated and take up so much of the rulebook? Why include a rule for a game that is only meant to prevent loss of immersion, rather than a rule that would increase immersion or even do both ?