It depends on what look the judges are going for.
Long post waring.
The uber-thick look, guys around 250 contest weight under 5'11", that seems to have been very popular until recently, is really not a good idea for a taller guy, as he has to be much heavier than that, to get a similar look.
BMI is not a good way to judge weight vs. height, as the math is flawed. The PI (ponderal index) is a better way to tell what is comparable for different heights.
For example, 250 at 5’10”, is the same as 346 at 6’6”. We have seen guys 5’10” and 250 pounds on stage, however there never has been a guy who is 346 at 6’6” on stage, and there is a physical limitation that causes this.
The heart has to work harder, both the taller, and heavier you are. Blood has to be pushed through all that beef. Noah Steere, who was as heavy as 347 pounds, in 2004, and at the time was lean enough to have stepped on stage at 325+, but was very uncomfortable with that weight. It was physically painful to be that heavy. Even though his silhouette would have looked similar in shape to a guy who was 250 at 5’10”.
So, in terms of possible, yes taller guys can get just as thick, but they have to be much heavier for it, and there is a limitation for how much a human, of any height, can be heavy muscle wise, until the health is put at serious risk.
However, taller guys can have very impressive builds. Someone who is 6’6” could for example be build like 5’10” 220 pound guy, at 300 pounds, which is realistic example, without keeling over dead at that height. However it is still going to be harder for him to maintain the same silhouette of 300 pounds than it is for the 5’10” guy to maintain 220.
This is partly due to the fact that taller, say 10% taller, does not mean every thing is 10% larger in every direction. The femur bone may be 10% longer, but only 5% thicker around. Therefor is will not sustain a quadriceps muscle more than 5% thicker around even though it is 10% longer, thus giving the visual effect of a quad that is less thick on a bodybuilding stage.
Someone at 5’8” will look like his legs are massive with a 32” quad. If the guy is 6’8” however with a 34” quad, people will say his legs suck, even if both guys can squat the same weight, and the legs are actually larger in circumference on the 6’8”, because visually (all that matter in bodybuilding) the legs look less thick compared to the rest of him.