There is a school of parenting thought where the parents don't use the word 'no' to their children. I found out about it when I overheard another parent at my daughter's nursery ask the staff whether they used the word. The staff were a little taken aback. I could see that they wanted to give the mother then answer she wanted, but that they were also thinking of the many many times a day they say it. "We only use it when it's necessary," one of them finally offered.
In my experience, it's often necessary. When my daughter goes to touch an electricity socket for example, or tries to eat a crayon. When she attempts to empty the kitchen bin or thinks 5am is morning.
I looked up the not saying no idea, or the 'No No' as I have started to think of it. Try to find an alternative to 'no', one book urged, suggesting that a toddler be distracted by a toy or an alternative activity instead. That way, it said, you can try to prevent your toddler entering the stage where they always say no.
Now call me old fashioned but I want my toddler to both hear and use the word no. I do not want to give her extra time to be electrocuted while I think of something as exciting as a plug to play with. I do not have the wherewithal to simultaneously find something fun for her to do with one hand while preventing her from running across the road with the other. And when she is faced with situations where she is offered a choice, you know - sweets from a paedophile, drugs from a big kid at nursery, a drink with spirulina in it, I hope she also says no, as firmly and confidently as possible.