For sound reproduction not much more is needed. But there’s nothing wrong with paying for esthetics, build quality, support (assuming Harman will provide more timely support than Roon Labs could) and all that stuff.
Is Harman actually claiming that it sounds better (or even in any way different) than a dumpster-dived PC one could throw Roon server on would?\
Customers certainly do. Manufacturers… I would not be so sure that all of them are that gullible. And of course this assumes that any specific “high end” kit is well engineered in the first place. Which very often is not the case at all. It is perfectly valid to pay for looks, build quality, service etc. It’s when claims are made that something affects e.g. sound quality, when it physically can not, that feathers get ruffled. Because even a Wadax (which is what… somewhere around 100K or something?) is still just a computer, just badly engineered, but not enough to make it sound noticeably worse.