I think to blame a chip company instead of the board manufacturers is the wrong approach
I somewhat agree agree with you here, but nVidia
is at least partially responsible:
1) At the outset, from what we can tell from the products on our market, even the best Geforce 2D implementation isn't up to the quality of Matrox's G4xx, so nVidia isn't completing for "best," but "very good." My four year old Matrox Mystique with a 170MHz RAMDAC has better 2D than a Geforce.
2) nVidia's spec for the reference design shouldn't be so loose as to allow some of the rather poor implementations out there. Remember, the majority of Geforce products out there are pretty much straightforward implementations of the nVidia's reference design. Yes, nVidia is in the business of selling chips, but poor implementations of their product don't help their reputation and, as you've seen here, the blame doesn't just fall on the OEM/implementer
3) When there appear to be so many poor implementations out there and very few good ones, the blame looks like it belongs to the core product.
4) nVidia gets blamed because it's easier to say "nVidia" than Asus/Creative/MSI/PowerColor/Cardex/Leadtek and countless other OEMs. Or to say "Everybody besides VisionTek/Elsa and Canopus". Fair? Maybe not, but see #2 and #3.
5) This isn't just nVidia-bashing. When pre-STB 3dfx sold their chips and reference designs much like nVidia, some of those OEM products had similar problems. In fact, I'd come across a fix for the Orchid Righteous Voodoo (a blast from the past) that's VERY similar to the fix circulating around for the Geforce's filters. I remember similar complaints about 3dfx quality that could/should have been placed on OEMs.
Ahhh, Canopus.....
Imagine the possibilities if 3dfx had merged with them instead of STB.
We can dream, can't we?

I doubt, though that they could have been the Duron of the video world. Canopus was always a premium product with a premium price, and unfortunately the price pressures from low-priced, lower-quality implementations drove them out. Their Ultra is a piece of work. Looks like it's clocked at 250/500, and has a copper plate over the RAM and GPU. Check it out
here. Heck, you know you can even change the video-out from 15-pin DB15 to BNC on their Geforce
MX? I'd seriously consider paying $200 for a 32MB Canopus Geforce2 MX, but I don't think there are a lot of us that would in the US. Especially with generic MXs running less than $100.