Difficulty is subjective, and the overwhelming majority of people have neither the same skill or time invested in any two jobs to make that assessment fairly. The 'highest skill job' for anyone is usually the one that they main. Most players have a hard enough time correctly evaluating their own competence, let alone trying to gauge job difficulty, and most public opinions on the subject are a reflection of whoever has been shouting the loudest.

If you want skill to drive gameplay, you stop giving out preferential treatment and level the playing field. Only insecure players are afraid of that, because you don't select for strong jobs, you select for strong players.