> In the interest of full disclosure, I tend to lean more conservative than most people, especially relative to HN. So maybe I have my partisan goggles on here, but why are so many people buying into the idea that there is solid evidence that Russia is actually behind these leaks?

Among other reasons, because cybersecurity experts who, insofar as they have partisan political bias that they might act on would be more likely to oppose Clinton and the Democrats than aid them, were the first to confidently attribute the hacks to specific threat actors tied to specific components of the Russian intelligence apparatus. (DHS and NSA much later jointly announced the same conclusion that private cybersecurity experts had previously reached.)