Server/Renderer vs. Oppo's simple app

Hey all ...  I'm going to dive into music downloads and Tidal so I've been doing my research on what do I need to get started... So its clear that we need a DAC, amp, speakers, file storage, and internet... but what I'm confused with is the front end... Oppo has a DAC (Sonica DAC) that has a simple app that can stream Tidal from the internet and can read your downloads and play them for you , while there's a lot of dedicated server/renderers out there for big bucks to perform the same tasks as Oppo's app...  So my question is why should I spend thousands for a server/renderer when I can get it for free ?  Did Oppo break the unwritten audio law of a simple app is all you need ? Is there an sound advantage of buying a dedicated serv/render ? Has anyone have the Sonica and tried both ways, with vs. without ?  The only reason I can think of why people would buy a renderer/server is because they already have a DAC that they like and/or tricked into thinking they need a separate unit...

thx in advance and value your input(s)

P.S.  it seems with the money I save on the renderer I can use it mod the Sonica (Modwright)