is there any reason not to get the ruger single six/ten for purposes of fun shooting and using the gun to increase my skill that will translate to skill with my next home defense revolver.
3 reasons, IMO. First, even for fun shooting, SA guns are a PITA to load & unload.
Second, if you mean home defense revolver to be a DA revolver, you definitely want to become proficient with a DA trigger. Different animal than SA, and getting in the habit of cocking the hammer can lead to a ND (or worse) in a stressful situation.
Third - Gripping SA revolvers is very different than gripping a DA revolver.
Get the single six/ten if it really calls to you, but IMO there's not much to it that'll translate to HD (DA) revolver proficiency.