What digital evolution?

I posted this as a reply in another thread, but believe it's thought-provoking enough to warrant its own post:

Is it really accurate that digital processing technology is evoloving (depreciating) quickly? The economics of technology don't seem to support this.

Unlike computer hardware which benefits from Moore's Law, and can therefore process more software at a given price point due to falling prices of memory and processor power, DACs are still processing the same 44.1 kHz software that is over 20 years old (not talking about high-res formats like SACD and DVD-A). DACs are not challenged with processing bigger programs at faster speeds that need more computer memory. Aside from upsampling, are there really improvements in D/A algorithms or other techniques that benefit from Moore's Law economics?

If this is true, good DAC design should remain competitive over time. Aren't the "best" DACs (Meitner, DCS, Weiss, etc) still competitive years after release? What technology is evoloving so quickly in D/A conversion?