It makes a tremendous difference, so don't downplay it. Infection due to smear (secondary droplet) is really high IIRC and washing hands is a huge countermeasure.
It's necessary but not sufficient to stop the spread. I'm currently just avoiding bringing the topic up with my sister who traveled from the UK to America last month. She repeatedly brushed off the topic because the UK government kept saying it's essentially the flu. Now she's in America with her 2 year old and I'm betting she'll probably fly back to the UK under these conditions.
It likely will. If all people washed their hands properly and avoid touching their face that would probably slow infection rates down enough. Measures are needed because realistically, no one follows these orders enough.
