I did a search for 18 mo, to see what sort of things I should be doing with my dd and for my dd, and also what sort of stages she should be at and have come away white with fear.
First of all there are people agreeing that their children talked in TWELVE word sentences at 18 mo. TWELVE! I've counted on my fingers, that's like, 'Mummy, I went to the park today and picked some white daisies.' Just daisies is just 11! Then there are posts where people are painting and clay modelling and glueing with their 18 mos. Mine has just about learned to hold a crayon, if I introduce her to paint she's just going to stick her hand in it. Or eat it. In fact, she eats the crayons.
Rationally, I suppose this site is going to attract the entire spectrum of abilities, so the top are going to be here as well as wherever my dd finds herself. But it really is scary.