The only PC desktop accelerator that could be considered early depth testing would be tile based 1996 PowerVR. ATI introduced HyperZ in 2000 Radeon DDR (R100), Nvidia followed in 2001 with GeForce 3 LMA. From what I remember Radeon compressed Z gains were surprisingly minimal, like 10-20% when turning it on/off, but Im sure it became crucial later on when real shaders (2.0) started being used.
The idea that we should ever allow companies to gate how we use hardware is a joke. The sustainability here is just wildly off the charts impressive. We as a species have blanket legal right to fix things we buy. Any legal monkeying that that from is us an affront to all of us, and if applicable whatever god or gods that made us.
There's no good reason to get emotionally attached to obsolete hardware unless you are running a museum or just doing something cool. AMD doesn't hack on a Radeon R100 for the same reason everyone else doesn't: it's obsolete. It makes more sense to get a modern bargain-bin $30 fanless graphics card than to make your R100 work in any modern computer.
I agree that this is more silly than practical or useful. It's just that old. It's ridiculous.
Reciprocally though 10 even 15 year old GPUs (half as old) are actually often pretty good and useful, for a lot of people. And they're what some people have. Many have multiple 100's of GB/s of memory bandwidth, which is pretty potent even today! That they can be so much better and that they do keep getting better is pretty amazing.
The biggest downside imo is power efficiency. A lot of these cards are on older hotter processes. They lack modern instructions and have to brute force various features. Some signficiant downclocking, undervolting can help a lot for this!
Consumer GPUs have really slowed in progress a lot, especially since 3xxx. With the pressure to upgrade diminishing significantly, I feel like there's an increasing need to have good long term support and care. I don't see anyone but open source as willing able or interested in putting in long term care for products in general. And the broader hope of open source: those willing able and eager to keep making sure the street can find its own use for things. That we can go as far as we might dream.
