Because they don't post on Conservative websites, blogs and chat rooms.
The 0bots goal here is to infiltrate the grass roots opposition to Dear Reader and fractionalize the opposition into competing factions by ginning up strife, discord and misinformation. Standard Marxism in action. Infiltrate so you can control, or destroy, the opposition.
Read any good history of the Lenin and the 1917 Russian revolution and you can see how successful these sorts of tactics can be