It doesn't really matter if the failure is at a weld or somewhere else. It has still failed.
If it can be welded by some elite few without the joint being a problem I guess you need to find out who those frame builders are, somehow.
As you are no doubt aware there are many steel alloys that have been developed for the sole reason of being reliably weldable.
Also other processes (brazing, lugs) for those alloys that can't be welded.