The question is what is the percentage of potential market for a specific product. If you are optimizing GPU code, that is a very different market from “all computers” or “all phones”. If the market depends on high performance GPUs, then the Ultra has potential to be a noticeable percentage of that market.

Well up until the M1 Ultra, almost no one was doing GPU intensive stuff on mac, since they didn't have a line with a decent gpu. As such, Apple is creating an issue for developers that only manifests on the $6000 version of their machine that requires rewriting your whole algorithm to work around.

Exactly. On top of that, Apple is still in the minority and refuses to support the Vulkan API they helped design. So, from a development standpoint, rewriting your software to support ~15% of your potential market isn't a very lucrative idea. Especially when the vast majority of those users will be running relatively incapable hardware, at least on the GPU side of things.

Well, this is already an improvement, the way the parent stated it: from "no Mac line with a decent gpu" to "only the $6000 version".

Well, over next releases, lesser Mac models will upgrade to something like M1 Ultra specs, as it happens, so that 0.1% is not exactly static.