The vast majority of what's showcased on that site and playlist were done via assembly hacks, not c.
Super Mario 64 decomp has only publicly been available since late 2019. And even then, there's still holdouts as the toolset for ye olde ways has been around longer.
Blender isn't competing with those programs, because those are a different type of software. Those are renderers, not 3D production suites. And two of the renderers you listed can be natively used in Blender in place of its own renderer.
Much of Pixar's software is entirely in-house. They already pay internal devs work on programs such as Presto. I'd be surprised to see them give up that sort of control.
> I specifically said Blender is not widely used in AAA game productions
This tells me you may not have been keeping as close tabs on industry practices. I can tell you personally, this has been rapidly changing over the past few years, and it's taken a lot of people by surprise. I can't say it's supplanted Maya yet by any means, but that software's quickly being seen as old-hat by each new wave of gamedevs. It's fascinating to see.
If you have examples of AAA game developers that have moved their entire studio (not individuals using Blender, or outsourced contractors making one off assets) to Blender I'd like to hear it. I'm aware that indies, including many successful ones, and potentially some mid-tier or AA studios, widely use Blender. I'm not talking about that. I'm talking about Naughty Dog, Blizzard, Treyarch, DICE, etc. I keep very close tabs on industry practices and work for a major game engine company. You yourself said "I can't say it's supplanted Maya yet by any means", I'm not talking about potential future growth, I'm talking about the current state of the industry in a very specific product category.
Simply put, a FLOSS alternative to professional software isn't an alternative if it's unable to be used professionally. The barrier for freelance and hobbyist work isn't people's concerns with dethroning these proprietary applications.
Can you get hired at a large studio with Blender on your resume? Absolutely. And Krita is slowly heading down a similar path.
GIMP, on the other hand, is dead-set on being relegated to a corner for FLOSS purists. It still doesn't have a complete CMYK workflow. It can't compete with Photoshop, and its authors have stated they don't want to compete. And until something comes along that can, people will continue to learn and use the proprietary option first and foremost.
This seems mostly true, but on “a FLOSS alternative to professional software isn't an alternative if it's unable to be used professionally”: Photoshop is not exclusively professional software. Last I knew, it costed $10 a month. That's a serious barrier to entry to exceptionally poor residents of slums within developing countries, like the disabled boy who lifted himself out of poverty with GIMP and other FLOSS (https://www.gnu.org/education/edu-software-gimp.html#content), but it's basically pocket change to privileged people in the first world like plenty of YouTubers I've seen use PS as part of hobbies like tiny indie gamedev. This seems like an OK niche for GIMP to target while Krita gets more professional. It's tempting to want them to unite and make one raster editor to rule them all, but it doesn't seem necessary. GIMP doesn't seem to need dedicated full time devs and effort comparable to 3D software, which is more inherently complex and in proprietary form is licensed for orders of magnitude more money than PS.
Super Mario 64 decomp has only publicly been available since late 2019. And even then, there's still holdouts as the toolset for ye olde ways has been around longer.