I often hear arguments along these lines:
Because X is higher level than Y, and X cannot do this, Y must not be able to do it either.
In other words, X must, because it is higher-level, be strictly superior to Y and Y cannot have any advantage over X.
Common extreme examples include:
Because minor image cannot produce intelligible speech, ghost sound also cannot, as ghost speech is a lower-level spell.
Because vocal alteration can't do anything but produce a certain kind of intelligible speech, ghost sound cannot produce intelligible speech, since ghost sound is a lower level.
Because minor creation cannot create non-magical objects (i.e. the effect disappears if it gets dispelled), create water also cannot create non-magical water, since create water is a lower-level spell.
Such beliefs seem to be in direct contradiction with the stated rules of the spells in question. A more pervasively problematic consequence is that low-level spells (especially level 0 and 1st) seem to suffer from extremely critical examination when compared to higher level spells.
Grease doesn't specify that it is flammable, so it's not.
Produce Flame isn't a damage dealing spell, because Dazing Produce Flame is too good of a spell for fourth level, but Mage's Sword is because it's a higher level.
My question isn't whether these spells work this way. My question is whether this kind of argument has some basis in the rules.
Is there a rule somewhere that I've missed that says that higher level spells have to be strictly better than lower level ones, or something to that effect?