Thank you for this interesting thought. My first thought was this. Why wouldn't I make furniture and sell directly to customers. Which is something I've been thinking of doing. One problem is that the computer desks I'm thinking about might not be what people want. Why? They will be expensive and it seems like the whole world thinks the IKEA desks are what they really want/need. Check some YouTube tech reviewers, the build game PC's worth thousands but they're nearly always put on IKEA desks because they're cheap (ish).
I guess marketing is at play there.