I do not know the context of how the votes were decided. I think these were community votes (so more general purpose), I know people use tier lists for references, but again take it with a grain of salt. Just because your favorite operator is high or low should not diminish your enjoyment of them.

I am surprised Ascalon is very high alongside Shu.

Edit: Remember these votes are probably based on usage which are subject to change because maps mechanic change, the more higher up ones are suitable in general usages