You're just replacing steel with steel, once it's welded in place it's one big piece of metal again.
The only real drawback to fitting rear qtrs are it's a lot of work, and you loose the factory sealed joints, hense panel beating and filler (in moderation)is a better repair in some cases.
You cut and shut a car that has severe front rear or side damage.
Instead of using individual panels you just use bigger chunks.
Provided that it's done properly and you follow factory seams it's an excellent repair method.
That it's a term loved by consumer orgnisations when highlightig botched body repairs.
If you look at USA MB parts websites you'll see front and rear clips, which are front and rear ends being openly sold for bodyshops to use to repair crash damaged cars.
In many countries insurance repairs can use used parts.
Ringing has all but died out, and ringers much prefer unrecorded cars as they're less likely to come under any inspection.
Don't forget this particular car looks far worse than it, if the wings, damaged doors, bumpers etc were taken off it, the car would quite alot better.
I am no metal expert but I wonder how metal reacts to traumatic shock and then being stretched back into place.
