[/quote]Or perhaps I should have dug out a slower CPU or disabled some cores and threads.
[/quote]
That was my first thought when you mentioned testing with the 1050, but nothing about testing another processor. It could be that both of these processors are too fast, or have too many threads to show any difference. Perhaps there's more of a performance difference when the game is starved for CPU resources, such as can be seen in some titles with a four-threaded processor, like Battlefield V. After all, it sounds like this feature is moving VRAM management to be handled by the GPU, so there could possibly be gains on the CPU side of things. It could be worth testing a few games that are demanding on the CPU after swapping in something like a Ryzen 1200 or an Athlon, or maybe just disabling some cores and SMT and cutting the clock rate back to achieve similar results.
Another thought is that if the benefits are entirely on the VRAM management side of things, a 2080 Ti wouldn't likely see much benefit due to it having more VRAM than current games require, especially at 1080p. The performance benefits may appear in situations where the VRAM is getting filled, and data is getting swapped out to system memory. If the card can make better decisions about what data to keep in VRAM and what to offload, that might be where the performance benefits are. You did test a 1050 with just 4GB of VRAM, but perhaps a 1050 isn't fast enough for this to make much of a difference, especially considering its not even managing 30fps at the settings used in most of these tests. Another site I just checked only tested a couple games including in Forza Horizon 4, but showed around an 8% performance gain in both when using a 1650 SUPER paired with a 9900K, but no tangible difference to performance with a 2080 Ti, so that might be the case. Of course, that wasn't a site I would actually trust for the accuracy of benchmark results. : P