Well, I watch this topic from time to time, though I never participated here.
I own a mbp 15 late 2013.
But for sure my new mbp, this year or the next one, will be the new 16'.
I want to tell my experience here, from similar product.
I bough such a case, external shell, plastic, almost transparent,
but not from a known brand.
It was good for many years.
Protection was ok regarding my mbp.
But when I finally decided to remove it after many years,
I saw something really bad.
The bottom part, the main body of mbp (keyboard, main computer, not the screen),
was slightly deformed!
I could not believe in my eyes.
It was almost a little bit of curved!
I could not see it all these years while the machine was inside the shell.
I seriously suspect the case about this deformation.
I think alloy is easy to be deformed as well.
I have to say that I am very careful about the handling of my computers, cleaning, etc.
I suspect that the external case I had all these years in mbp,
somehow internally supported the machine in wrong angles,
and also the absorb of the pressure on the track pad, may have played a role too,
because mbp was not all alone on the desk but inside this shell.
Do you observed such bad incidents yourself?
I know that many of you possibly do not keep your machines for so long.
Or possibly the branded cases are really better in this topic?
I do not know.
All I know, it is that I really want an permanent external case for any mbp I own,
but I do not want to face once again such situations.
I want to hear your opinions and experiences.
In short I have had zero problems with any case & certainly not to a point of bending the MBP.
I always use a hard shell case & my 2015 15''MBP is absolutely spotless scratch dent free with only key wear evident.
I would have no idea why your MBP could have suffered from this & is odd.