Gloomhaven/Frosthaven are a great example. Playing those makes me realize that like, as much as I might like tactics and optimization, there is clearly a line beyond which it becomes deeply tedious to me, and basic competent play in those two is definitely way over that line! But I know the sort of chess club math nerds I used to play D&D with would absolutely love the to-me-incredibly-tedious strategizing and analysis of options the Xhavens are all about.
Xhaven is a bit of a different beast. It's certainly complex, but the complexity is on a tactical level rather than a mathematical one. You're generally not doing math that's more complex than adding two single-digit numbers. The complexity comes from, essentially, resource management: you have a hand of up to 14 cards and have to choose two of them to play for every round. Each card has a top and a bottom, with the top often (but not always) being an attack or other proactive thing and the bottom often (but not always) being a move or other support ability; and you will need to use both a top and a bottom ability in the round, but you don't have to decide which is which until it's actually your turn. When you've played a card, it usually goes to your discard pile where it remains until you rest, at which point you recover all your discarded cards except one which goes to the lost pile. If you take a long rest (a full round), you choose which card to lose, otherwise it's random. And some powerful effects go straight to the lost pile without being discarded. Some cards can have a weaker effect now, but set up an effect that can make a later card more powerful.
This creates an enormously complex game, which can honestly be pretty overwhelming. But the math itself is pretty simple.
No, it doesn't support that idea.
It supports the idea that TTRPGs aren't the right place for complex math-centric rules design.
And frankly they never have been - as I said earlier, the actual math and game design in the earlier, more complex and math-centric games wasn't high quality.
The problem is that it's pretty common to assume that just because something has complex math, someone must have thought long and hard about it and therefore it must be realistic. My favorite counter-example to this is the 3e rule about the availability of goods. Basically, each settlement has a certain max gp value which determines the most expensive things to be found in that settlement, and which depends on settlement size in different categories (ranging from thorp through small/large villages, towns, and cities, and eventually reaching metropolis size. But if you wanted to know how many of any given good you could find for sale in town (e.g. you want to buy swords for your whole army), you would multiply half the max gp limit by 1/10 of the population, to get the total gp value of any given good available. So Waterdeep had a population of 132k in the 3e FRCS, and a gp limit of 200k. So for any given good, you could find 1.32 billion gp worth of that good in Waterdeep. Since a chicken is worth 0.02 gp, that means Waterdeep has 66 billion chickens for sale. Or 44,000 galleys. Does that make any god damn sense? No, of course not. But it's a rule with math in it, which makes it
look reasonable.
Not true. One of the members of my previous group bounced off 5e hard, precisely because it lacked the complexity that he craved.
Math complexity specifically, or complexity in general? There's a player in my group, who's generally the one who digs down the most in different games to explore various options, who doesn't really care for 5e because of the scarcity of options. Basically, after level 3 when you've chosen your class, background, race/species, and subclass, your character is more on less on rails mechanically. OK, you still get to choose ability increases/feats, but that's only once per four levels. Compare to Pathfinder 2 where you make at least two choices per level (class feat + skill feat at even levels, and skill increase and alternating between ancestry feat and general feat at odd levels), and occasionally adding more to that. That's not necessarily more math-intensive (though in the case of PF2 it is), but it definitely provides more complex choices.
Which is why burning it all down and starting over (and over) is so disatisfying. I hate reboots.
I've come to the conclusion that rebooting or drastically altering something that's active is usually a losing proposition. You lose many of the current fans who won't care for the changes, and non-fans will not be likely to flock to the New World Order because they already have an image of what the thing is in their minds and have already decided that it's not for them.
It can work out for properties that are basically abandoned, because whatever current fans there are won't feel like they're
losing anything – there wasn't anything new happening anyway, and the difference between "getting the thing in a way I'm not into" and "not getting the thing" is rather academic. You didn't see an uproar among old TORG fans about TORG Eternity because TORG had been dead for decades anyway (of course, it helped that TORG Eternity was pretty nifty), but when Wizards blew up the Forgotten Realms in favor of the 4e version people got quite upset.