There are a few things that I probably would never have found without a guide but the majority give you clues.

FFX does say you get rewards for dodging lightning. People are bound to keep trying to see what is the maximum reward. Below '0' on Chocobo racing would be similar as well. People will want to try and get the best times. Also, the chocobo sage in FFVII tells you how to get an Ocean-Crossing Chocobo (once you've jogged his memory enough). Once you have it, a tad more exploring leads you to KOTR materia.

I agree that not everyone is good/patient enough to do all these things. I always use a guide on my second playthrough of a FF game to get all the things that I missed.