Some proto-writing systems (e.g. Australian message sticks), which could not express all ideas, were just very simple dots and lines. Going from being able to express only certain things to the full spoken language and going from complex symbols to simple ones which are easy to write are two different processes. So while we can suspect that a pictoral system is from an early stage of a writing system we cannot say that it is necessarily primitive in ability to express all ideas. Plus it might be, like hieroglyphs, only used for fancy texts for monuments and similar.
I'd wager the Great Pyramids will still be around in 1000 years and the Burj Khalifa will not, if anyone wants to take bets.
The closest analogy might be: modern alebraic notation is compact and clean but this doesnt mean algebra didnt exist much, much earlier.