I think OP has a legit question.
The answer is, yes, one could glue the rubber a cm or so higher than the handle per the Laws of TT>
2.4.3.2 Sandwich rubber is a single layer of cellular rubber covered with a single
outer layer of ordinary pimpled rubber, the thickness of the pimpled rubber
not being more than 2.0mm.
2.4.4 The covering material shall extend up to but not beyond the limits of the blade,
except that the part nearest the handle and gripped by the fingers may be left
uncovered or covered with any material.
As to what Carl said, I have added weight to the handle of so many blades I had Carl try, I cannot remember, but I did it once to a Qabod.
I would only move up a sheet of rubber on a blade if I had a tear right at the top of the blade and no replacement sheet of rubber. Legally for a tourney, I could do that... but there would be a cost... the balance is now affected to be more head heavy as I lost weight down low.
Adding weight to the handle, especially if you wrap grip tape the right way, can really increase legerage and whipping action using fingers and wrist.
That counts for a lot in low energy situations like a flip... or big power shots. Having the ability to make 5-10 more power is huge. You get easier power from a bat with the weight balance lower. Also a good feel at impact.