The thing about playing strength in games like go is that it doesn't map at all linearly to results. It could very well be the case that the bots are only a few points of handicap away from perfect play, but thousands of points of ELO.
I wrote about all of this on Stack Exchange, along with some napkin math, a couple years back: https://boardgames.stackexchange.com/a/61058
Anyway, this is a poor argument for a possible "limit to intelligence" because of course the game is finite (even if the search space is extraordinarily large). Of course you can't beat the "hand of god", by definition. Of course you can create games and puzzles for which "hand of god" is a coherent concept. It shouldn't be too hard to specify games where it isn't, though (perhaps something involving real numbers).
And that's not even really touching societal/network intelligence. A single human isn't that smart and can't accomplish that much. Hence we form families, and companies, and societies, and governments. What does a society of AIs look like?
And a society of humans does not increase our overall intelligence. It allows all of humanity to access the accomplishments of our most intelligent members throughout history (which is huge, don't get me wrong!) but it seems almost self-evident that our civilization as a whole is not smarter than Newton/Einstein/von Neumann/etc.
If I dump Einstein on an island at 5 you don't get a theory of relativity. The data provided by a civilization is required, hence why people 10,000 years ago didn't go to the stars. It is unlikely they were significantly less intelligent than us. They just didn't have the language of data we do now.