DT Swiss XR 4.1 d Rims for Disc Brake

The XR 4.1d is the disc brake version of the DT Swiss XR 4.1. It has an identical rim profile, but with machined, then black anodised, sidewalls. Is it necessary for a disc rim to have a welded joint? A disc brake doesnt need a perfectly reworked joint for good braking. But the SBWT (strength boost welding technology) makes such a structurally perfect, tight rim. So why not take advantage of it? Weight: 425g, Width: 21.6mm.