It's a matter of some debate whether they had true writing. Michael Smith, over of the most notable experts in them, leans against the true writing argument because there are sentences possible orally that can't be communicated in writing. That would make it another form of the proto-writing I mentioned.
Plus, many of the groups around them did not use the same script despite having comparable levels of technological development. The Maya, who did have true writing, were not massively more advanced technologically.
Plus, many of the groups around them did not use the same script despite having comparable levels of technological development. The Maya, who did have true writing, were not massively more advanced technologically.