Streamer observation / question to those who know

I'm not sure I know how to phrase this post so I may ramble please bear with me. It seems that most the new DACs have "I2S" ports yet the higher end streamers usually don't (yet maybe???).  Yeah I know there's no standard and they can't even decide between HDMI and RJ45 plugs but a 12K N20 streamer doesn't even try.  It's already or almost obsolete.  AES/EBU is purported as the premium interface but it's usually limited to PCM: Up to 32-bit / 192 kHz; DSD: Up to DSD64 via DoP.  So does that mean everyone was wrong about USB? Is USB fixed now?  If so why is I2S so prevalent on the newer DACs, is that just marketing or do DAC manufacturers know something streamer manufactures don't?

Upscaling to DSD may be fad like MQA but some DAC manufactures seem to believe in it, going so far as basically putting two separate DACs into a single box and supporting up to DSD1024 and PCM up to 1.536MGHZ.  To perform that kind of on the fly conversion from flac to DSD takes a lot of CPU/GPU power but it should be possible with in a quiet box, with a linear power supply, an optimized OS and a I2S board for a lot less than 12K and at least supporting the current technology included in today's DACs.  An even cheaper solution would be forgoing the DSD1024 with a i7 fanless computer and a DCC add a linear power supply and for less than a quarter of the cost you should be able to reliably stream DSD 256 and probably DSD 512 thru I2S.

So,  What am I missing?  I'm not saying a high end streamer doesn't sound better than a dedicated PC (I haven't compared them) I just don't know what's in the box that makes it better that much better. With the limitations of its' processing power and interface should a high end streamer even be considered based on today's DACs?