actually some r and b and blue songs use 3/4 or the faster 6/8 like for example, "I'm your baby tonight." By Whitney Houston. It hit me like last night in my bed as I was thinking about the song. The song is 6/8. Crazy things I figure out when I'm laying in bed awake. 3/4 is usually used for swing too. Not just waltzes and country.

It allows for more of a syncopated beat.