Well...
So, using physical sports.. a match in a FG takes a few minutes to get in to (or less) and a few minutes to finish and has little to no physical and mental effect on tbe players until hours of straight matches have gone by. Physical sports require immense amount of money and effort to move around these huge organizations, house the players, the games themselves are an all day affair once they start and are weeks in the planning and take a severe physical and mental toll on those participating. Physical sports don't match up here at all. If they COULD have. 2/3 setup or something they would.
Not to mention many do, and has been stated previously - this just doesn't fit as a reason to keep ranked one and done.
You keep mentioning casuals.. and how "well what if they want to compete with each other on the leader boards".. etc.. well, that's too bad I guess? What you're asking for is a mainting a flawed system because it benefits a minority of players.in the system, who the system isn't designed for in the first place - and I just don't understand that.
It's asking competitive players to be less competitive and accept an inferior experience in the mode DESIGNED for them so a small subsect of casual players can be catered too.
I appreciate the measured and reasonable way you've argued your points but I just feel like your on really shaky ground, and ultimately the argument doesn't make a real case for one and done remaining, nor does it reflect to the views of the VAST majority of ranked players. Certainly decisions should always be about majority rule, but tailoring a system designed specifically for a specific majority, to cater to an outlying minority, I'd a losing proposal from the get-go. It's like throwing giant mud tires and huge metal stack exhaust pipes on Camrys because there's a small handful of Camry buyers who actually want large diesel trucks.. and for reasons largely unknown, didn't choose to buy one in the first place.