IMHO, Disney parks are evidence to the contrary. EPCOT, Disney-MGM (both in their original themes, of course), AK... definitely not heavy on rides. Several non-Disney brands have also shown that rides are not required. Universal Studios in Hollywood was extremely popular, without having any real rides for many years. Also, Sea World for many years had no real rides.
I think that is the difference between an amusement park and theme park. Each has a different business plan for attracting guests.
My personal opinion is that most of the parks I noted have strayed from their original vision just to compete with Six Flags types of parks, and that those changes take away from what made theme parks special to begin with.