If you want to argue that the combat mini game is a treadmill, then as I said, I could see that argument. I'm not convinced that it's actually accurate, since high level characters gain combat capabilities that low level characters can only dream of which can significantly change the nature of combat. But I can see the basis for the argument.
Some do, most don't. They mostly gain different fictional positioning. The monk hits more often, for more damage, can snatch missiles out of the air, and run up walls. The combat stuff is the focus of the classes (and the game, as you admit below) and the non-combat stuff is mostly fictional positioning...which only matters if the DM runs a game where that fictional positioning actually matters. Like someone with the Outlander background in a city-based urban campaign. Sorry. Tough luck.
Combat isn't the game though. It's part of the game, but far from the entirety of it. Maybe 40-50% in total in my group.
Right. One of three "equal" pillars of play takes up 40-50% of your game. Seems like even if it isn't "the whole game" it's clearly a very big defining feature of the game. This is further supported by the fact that non-combat stuff is basically non-existent outside of the odd spell for shenanigans.
Let me try to put it another way. If you have low level supers with super strength and toughness, and high level supers with super duper strength and toughness, then you're likely dealing with a treadmill. They're doing the same things at low levels as high levels, just better.
Which is what the vast majority of D&D presents. More of the same and bigger numbers...with the occasional actually new thing. They're mostly simple gradations of improvement on a concept. You like throwing fire on people from far away, we have dozens of variations of throwing fire on people from far away. Throw a small fire on one person at a time. Throw a slightly bigger fire on one person at a time. Now throw a slightly bigger fire on one person at a time. The progress is staggering.
Yes, forcecage and polymorph. Those are fictional wrappers for "neutralize the enemy without killing them". They're just more or less advanced. More or less easy to resist...and since the enemies' resistances increase as your ability to inflict unwanted conditions on enemies...you're on the treadmill. Your numerical position
relative to the on-level enemies doesn't really change. It's smoke and mirrors. You every so occasionally get a new trick, but that's it. All I'm saying is you can skip the treadmill and go straight to the new tricks.
If you have low level supers with super strength and toughness, and high level supers with all kinds of crazy abilities (flight, telekinesis, invisibility, telepathy, etc) you're likely not dealing with a treadmill.
If the baddies advance to match the heroes...that's a treadmill. Batman punches bank robbers. Superman punches gods. The difference is fictional positioning. The DM lets Superman throw mountains, the DM restricts Batman to throwing batarangs...and fits when the stock market crashes. You don't need set numbers to represent the differences in strength between them.
There's a variety present in this latter case that isn't present in the former, which will almost invariably lead to a difference in gameplay. It doesn't matter whether or not the numbers are also inflated. Numbers aren't the entirety of the game.
Tell that to the majority of players and designers. They seem to be completely enraptured with the numbers and that seems to be all that matters to most of them.
