Where did you see this? That is not what I read in @beowulf’s posts at all.
How does one even show at a higher level than they are schooling? That seems like a silly thing to do (both financially and for the well being of your horse).
I have no problem with a clinician pointing out that my body shape will make something more difficult. I would hope it is followed by helpful tips on how to overcome this hurdle and be successful even with this body shape. Which is then useful to everyone listening because there is likely someone auditing that also has a less than perfect body shape to make things happen.