What IKEA is good at is continuously decreasing the work involved, error rate, quality issues etc. I can see no practical purpose to folding the metal yourself in this case, other than to make it feel more special than it is.
The final assembly is the most labor intensive part of our process. When we get an order from one of our retailers for 10+ products, it takes us a full day just to build/test/pack, because of this.
By selling these as "Ikea style" I promise they're able to massively reduce the cost for consumers by outsourcing their assembly.
Also, deciding to do DIY assembly changes how you think about / plan the design + manufacturing of the object, because you aren't training a workforce to assemble specialized parts, but now need a system that most people could pick up and assemble without any major mistakes. It's more design and thinnking, not less.