If they chose, improving gaming on iOS/AppleTV could be a big win for them. But there is no evidence that Apple cares about gaming at all.
Therefore, there IS a point in building more powerful Macs: serving markets that are only unserved because the hardware isn't powerful enough.
Gaming isn't the point. My interest is in developer machines, but illustrating that more powerful hardware is NOT pointless is more easily done with the gaming market example.
Apple doesn't want to serve these markets. There will always be some people who can find a use for more power, but they aren't Apple's market. For one thing they usually care about price/performance, and Apple refuses to play that game.
For those developers that only care about WWDC, and their main income is programming macOS, iOS, tvOS, watchOS applications, the only requirement is being fast enough to handle XCode.
For those scenarios most Macs are already quite good and these are the developers Apple wants to keep happy, not those that buy Macs as an UNIX with a pretty GUI.
The toner-head argument is basically that decisions are being made by sales and financial teams who don't understand what they are selling.
I'm making multiple arguments here, but none are the toner-head argument:
Argument 1: iOS is a better platform to move into gaming on.
Argument 2: The compromises needed to make Macs good gaming machines are completely different to the direction Apple thinks is good for the Mac.
Argument 3: Apple has never cared about gaming.
Really, this is a very long and complex discussion, but I just wanted to point out that Argument 3 was not really accurate.
Other than Prince of Persian, I don't remember a single one.
Then again, in Portugal outside the university campus there were no Macs to be seen.
Yet we had Amigas, Ataris and PC everywhere.