Not true really.
Mostly, because the domain although a factor, is not the main factor but content and links.
Second, as far as google goes, the algorithm changes all the time.
I believe that this "hyphen is better for SEO" is a myth nowadays and not true anymore with most engines.Not saying a hyphen name would have worse or better chances than without, just saying it's not such of a factor anymore.
One hint: The ovt suggestion tool in most cases shows you the searches for the term *with* a space in it even if you entered a term *without* one.
In fact, the only time it shows searches without space is when the term has enough searches as one word on its own as well.
There is a lot that could be said about SEO and diff people have diff experiences/opinions..
