How are most audiophiles going from streamers to DACS

Newbie question, looking to purchase a high resolution streamer.  What I don’t understand is people hooking coaxial digital or optical to their receiver.  I thought optical and coaxial didn’t have the full resolution that hdmi has for the new formats.  If you’re using a high quality streamer, even with a decent receiver, shouldn’t you use the the RCA out to take advantage of the DAC from the streamer?

Thanks!