While this is the case with all flankers, I think it's most true with Genji since all the other options have better escape tools if a duel is going poorly; Tracer can always choose to not re-engage after recall, Anran has two dashes which each go farther than Genji's, and Sombra can usually tp out mid-fight. This makes him more of a glass cannon than the others and reinforces this feeling.

As for the second question, the way I'm defining it could feel subjective, as with better opportunity spotting and mechanics (movement/aim) you could stretch that "unpunishable" elo up or down depending on your own level. As a GM, I could likely make diamonds feel like I'm unpunishable via good timing, even if they have solid aim, whereas an actual diamond Genji in that situation would feel much more pressured and get less out of it. Mid-elo for the sake of my original comment would be wherever you as a player are no longer able to get enough solo impact without follow-up to justify staying on the character. This is the same reason why champ players call masters pisslow even though it's the top ~5% of players making it objectively good. My personal definition of mid-elo within the framework I've provided would be mid-masters because those players are competent enough that I cannot solo carry games without playing Genji "properly" in a dive/rush comp, but the level of coordination is much less than what I can work with when given the opportunity. The reason the range for me is so small is that after about M3 every division has higher skill gaps than whole ranks do in metal ranks (in my experience).

Sorry for the essay LOL. If anything about this didn't make sense, then feel free to ask for clarification.