It's not misinformation, that is my experience from playing the game: the schools affect the culture rating because it helps to provide more entertainers to stages which may not be staffed and therefore, those houses will be covered and contribute to the culture. Placing a stage does nothing to culture if it isn't staffed and active, which is pretty well know.

Also, just because one user made a post about it, doesn't make his word the absolute truth. What matter is your own testing and knowledge, other people can just easily be wrong (and that article is many years old from my recollection).

So in conclusion, we have:
Shukaku's recalled experience from a while ago

Versus

At least two of the most prominent Pharaoh websites (Pharaoh Heaven and Which Way to Thebes) saying otherwise
My own current testing confirming Shukaku is incorrect

Unless there's multiple versions of this feature, or regional differences, it's only fair to let people make their own decisions about this based on the evidence provided :)

Regarding bouchacha and shukaku:

You are both correct under different circumstances. More schools (juggling schools, conservatories, etc not to be confused with scribal schools) DOES affect culture rating IF (and only IF) some stages are unmanned. However, if you check your current stages and they are manned (using culture advisor and then count them on your screen) and culture rating is still low - then it's a numbers game - you need more stages (which you should also build more schools for generally). The acceptable ratio is somewhere between 1-3 stages per school depending on how far they walk and a few other details which are much better explained in the "Got your culture right here" post on Pharaoh Heaven.

Please note that this is different than libraries which do NOT have to be supplied with papyrus to count. This has to do with the way the game counts them - manned stages affect a fixed (300 for booths, 1500 for pavillions, etc) number of people. Unsupplied libraries and scribal schools (using papyrus normally) affect 700 citizens and 300 students respectively whether or not they have papyrus. They only need papyrus if you're playing by personal rules or you need them to evolve housing when they patrol.

Culture, religion, trade and every other topic in the game is explained in minute detail on pharaoh heaven - it's free to login and there's a sticky in the forum to useful posts including culture. Also, just about every bug ever encountered is explained on there too so it's a great place to check if you don't know the answer yourself.