It does look a little cool, but I always worry a little about the reliability of the cable itself. Does it REALLY meet the signal integrity specifications for PCI-E? Probably not. But, no unexplained crashes or glitches so far and this build is over 2 years old.
You'd want to somehow monitor the PCIe bus error rate - with a marginal signal and lots of errors -> retries, something that loads the bus harder (loading new textures etc) could suffer way more.
They do briefly show a different PCIe riser made out of generic ribbon cable [1, 3:27], and say that one failed after chaining only two ~200mm lengths. The quality of the riser cable certainly matters.
The 650 Ti is PCIe 3.0. PCIe 4.0 doubles the bandwidth. PCIe 5.0 doubles the bandwidth again. The RTX 40 series GPUs still use PCIe 4.0, which have commonly available conformant riser cables. I suspect the story for PCIe 5.0 will be different.
PCIe extenders are a thing already. Current PC case fashion trends have already influenced the inclusion of extenders and a place to vertically mount the GPU to the case off the motherboard.
GPU sag is also a bit of a silly problem for the motherboard to handle when $10 universal GPU support brackets already exist.