Yes, but there are economies of scale that Dell or Apple enjoy which will never apply to a seller targeting a niche market.
Not only do they get lower costs on parts, but they can afford lower margins per unit since they have much higher volume relative to the fixed costs of running the business.
What the thread parent (bgorman) saying is that boutique desktop systems (as with any niche product) have to add significant markup. But, for computers, the target market of these manufacturers can also often build a computer themselves and avoid the huge markup.
If you sell ultra high quality waterproof headsets to audiophiles for $2500, including a $1000 markup, your customers have only the choices of A) not buying or B) paying the markup. With desktops, they get the 3rd choice of building it themselves for $1600/1700.
Not only do they get lower costs on parts, but they can afford lower margins per unit since they have much higher volume relative to the fixed costs of running the business.