The control required to master SC2 is far beyond any MOBA style game. AI for MOBA games seems trivial compared to AI for a large scale RTS. It's the difference between controlling 1 unit vs 100 units.
I might argue that the AI vs AI challenge in Starcraft is deeper and more difficult to master. But for AI vs Player the Starcraft AI has an enormous mechanical advantage. Being able to harass mineral lines in four different places is a big deal. Being able to perfectly micro multiple lines of attack/defense is a big deal. It's very unfair and very much in the AI's favor.
Chess < Go < Starcraft < League of Legends
In my moderately educated opinion.
Control them, sure-kiting 100 units at a time would be a breeze-but using them together in a coherent way is drastically more difficult.