There have been no cards that can do hardware mixing under production for more than 15 years. This is delusional.
Also, the cards that could do that back in the day were, audio quality speaking, shite.
If that's really what you consider "the best audio linux has ever", I think you don't know audio on linux very well.
I will grant you one thing: if you did have one of those cards, it certainly made multiple applications all playing (same sample rate) audio at the same time as easy as it could be. But that's all.
That's totally the exception however, whereas back in, say, 2000, such devices were the norm. These days, the current crop of prosumer/proaudio audio interfaces (both PCI and USB) do not offer this sort of facility.
Also, the cards that could do that back in the day were, audio quality speaking, shite.
If that's really what you consider "the best audio linux has ever", I think you don't know audio on linux very well.
I will grant you one thing: if you did have one of those cards, it certainly made multiple applications all playing (same sample rate) audio at the same time as easy as it could be. But that's all.