I think there's an intelligence limit, or at least asymptote. It may be above human intelligence, but I don't think it's miles above it (at least not the kind of intelligence humans can create, recognize, or use). For example in Go, most estimates place God or "perfect play" three ranks above top professionals[0]. In the latest human-AI Go match, the human got a 2 stone handicap. So it's not like we have a lot more frontier to push there.
Intelligence is spiky. In some things humans may play near the limit (Go possibly), but if you look at parts of mathematics like addition, humans can add in their head just fine but its a few trillion times faster to use a computer on addition problems of any size.
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?
this assumes our whole universe and what we can do in it is a finite go board. maybe it is. but we are no where close to exploring even a fraction of it. lots of things need to happen before any limit is reached. the cavemen would also probably think we saturated tools once they saw bows and arrows.
Just FTR, Shin Jinseo's result in that latest match is seen as extraordinary. In the last few years it's been common for top pros to play bots on 3 or even 4 stones.
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).