There is one crucial difference between image editing software like Photshop and Gimp vs. 3D software suites like Maya and Blender: My hypothesis is (and feel free to pick this apart) that you can totally teach yourself to use the former rather competently without any outside help, not even documentation and tutorials, but I would argue that this is nearly impossible with the latter due to their far greater complexity. This in turn means that people will look up guides and tutorials and learn the idiosyncratic UI patterns that way, which is why Blender with its extremely nonstandard controls managed to gain a foothold far beyond the broke hobbyist sphere.
Thanks for gently letting me down on RISC OS. I guessed that there wasn’t much going on with it, but I wanted to be sure.
What matters is that TI has an effective monopoly on scientific and graphic calculators in the US in particular, which means that it’s the platform that matters to most. It’s irrelevant whether or not some alternative is better. It’s also extremely widely supported by software and tutorials.