Hyphenated domains lost Googles love long long time ago.
That's interesting, because I had an EMD that was kw1-kw2-kw3.com that was number 1 and 2 for years, alternating back and forth with another guy who had kw1kw2kw3.com.
The phrase itself was 3 words long, so it wasn't like a keyword stuffed domain.
Anyway, last year my site dropped off the map and his is still number 1 and number 2. His site is like 1 year older than mine, and mine has higher pagerank, DA, PA, mozrank, moztrust, more backlinks, more content, etc. The only difference is that his doesn't have hyphens.
I even submitted a reconsideration request to Google about my site and they replied and said nothing suspicious was detected. So it's not even like I got penalized for spammy SEO or anything.
So it's possible you are right about the hyphens.