Article is from May but received no attention, and I believe most people are unaware of this; the Mac needs an iBoot on the internal drive in order to boot from any volume, and thus cannot boot from an external drive if the internal one has failed.
I hate the soldering, too. I'm just offering an explanation that may make some sense given the context.
This was pre-2013. So perhaps the proprietary connector was a reaction to the cable?
You could make it so there’s a break glass copy of iBoot on another chip, but then that’s something they can’t update if there’s a bug.
To be fair if you or your company are dumb enough to buy these devices your probably also of a mind to take it in for expensive repairs.
Its perfect business logic from the fruity chaps.