performed any comparative tests to verify this i would be curious to know the science behind it. i have always advocated in heating the sugar for the exact reason you mention. i do the same thing with my nibs and i melt any cocoa butter i am using. it all adds heat to the melanger and helps it get going...
moisture could also comes from heat, if a fruit is exposed to high heat like in an oven, it starts cooking right away (even if it just a few short minutes). thirdly, having a fresh fruit means it's going to deteriorate quickly at room temperature. all in all, having a fresh fruit in a cookie is just not...